Apple Watch Jailbreak

Apple just seeded beta software for upcoming versions as watchOS  4.3, iOS 11.3 and tvOS 11.3. A couple of days ago they released watchOS 4.2.3 for Apple Watch, iOS 11.2.6 for iPhone, iPad and iPod, tvOS 11 for Apple TV as the latest versions. iWatch series 3 is the latest iWatch which was released with improving software and hardware features.
Steve T-S confirmation for iWatch jailbreak
Steve Troughton-Smith ( Irish programmer for Apple software), Saurik (Developer of Cydia) and Adam Bell (Canadian software developer for Apple watch) was able to hacked Apple watch and ran UIKit & SceneKit apps on the watch device. Proven video as follows.
 Cydia and Developer Adam Bell
Hamze sood jailbreak
Another Developer Hamze Sood able to run Flappy Bird on Watch OS 2 and users can control it by touching and handling Crown.
Hamze Sood able to run Flappy Bird
Web Browsing by Comex
It has no safari web browser to the Apple watch and even in future, it will never be added because of the small display resolution. But users are interested to have it.  So jailbreak is the only solution to do it. As expected, the Web browser released by Comex and he could run Google Home page, and Copy/Define option is running on watch display. Here are the Twitter image and video confirmation of Comex web browsing.
Comex and he could run Google
Third Party Watch Faces
Free time face
Free Time Face by Alexander Zaytsev
Basketball face by Plearns
Plearns has created several faces to watch interface. Basketball face was one of the smart faces, which his made first. Once the jailbreak release for iWatch, users can use all of his faces.
Basket Ball face
Japan face by Alexander Zaytsev
This is another face which create Alexander. Also he created time telling apps / themes  for iWatch. Unfortunately still we can not use all because there is no any jailbreak method for iWatch device.
Japan face
Meditation face by Mackenthun
The Mackenthun is another jailbreak app developer for the Apple devices. He has been created many number of applications / wallpapers for the third party app installations.
Meditation face
Sunset face by Martin Eriksson
This is a very beautiful upcoming jailbreak custom face. We have not idea about , why Apple not include this face for default list. However, all iWatch users will be lucky to install it after jailbreak.
Sunset face
Running Face by  Michael Martino
This is also very creative watch face, and it is displaying past and now running speed. This specially created for athletics players and other users can use too.
Running Face
Nike fit face by Geo1
It is depended to official Nike Inc. Nike Company asked to Developers to create a watch face for Nike. Then Geo1 team has created this watch face for Nike Company.
Nike fit face
Behance face by Tyler Gough
This face can customize the watch face according to user’s choice even users can add their own image. Other faces can not change. Because of the customization ability, this face will be most popular among the users.
Behance Face
Watch Clock 2nd by Martin Eriksson
This is very attractive face with the good color balance. It is displaying time and weather forecast according to your current place. Because of these features this will be most popular custom face among the users too.
Watch Clock2
Music Mockup face by Martin Eriksson
It has a nice 3D look. Most advantage part is users can be stream music directly with this face. Users only need to do hold and touch the face and here after it asks from you to stream the music. This will be famous among the music lovers.
Music Mockup face
Watchface by Judesh
This face created by one of Israel Developer. When compared with other iWatch faces, this has very simple design. Because of having simply design, it will be popular.

watchOS 3 Jailbreak by Max Bazaliy

Hacker Max Bazaliy was demonstrated about watchOS 3 jailbreak at World's largest hacker conventions of DEF CON which was held on 27–30th July 2017. At the presentation, he has targeted to access following sensitive information.
Watch have access to SMS, Calls, Health
Photos and emails synced to Watch
Fetch GPS location from the phone
Microphone usage
Apple Pay
However this jailbreak was done privately and he did not hint about public release.

Jailbreak WatchOS 2 & Minor versions

Keen Team proved the possibility of iOS 11.1.1 Jailbreak  at PoC 2017 and iOS 11 jailbreak at MOSEC 2017. However, they did not release any public tool until now. Also, It has many jailbreak solutions for these versions such as LiberiOS Jailbreak, C0F3 Jailbreak, Electra jailbreak and To.panga jailbreak.
Phoenix Jailbreak
Phoenix Jailbreak released jailbreak tool for 32-bit devices running on iOS 9.3.5 versions. This was released in collaboration with Siguza and tihmstar.
Yalu online jailbreak
It has two Yalu jailbreak methods for iOS 10 to iOS 10.2 jailbreak. One method can complete without getting PC help. Other method asks PC support. Both methods work as semi untethered. Click the Yalu Jailbreak page for more details.
Some good news for watchOS 2 jailbreak has follow.
Alexander Zaytsev introduced many new faces at WWDC event keynote session before releasing the iWatch. Apple launched the few faces when iWatch releasing and some of them rejected. However, once jailbreak method confirms Alexander Zaytsev will introduce more new faces and then we can use all faces.
iOS 11.2.2 Jailbreak
Anzhuang and Velonzy jailbreak app installers allow you to install jailbreak apps for iOS 11.2.2. Also, it has many jailbreak scams for this versions. Do not forget to download Jailbreak tools always from trusted sources. Visit iOS 11.2.2 Jailbreak page to get jailbreak info about iOS 11.2 to iOS 11.2.2 versions. 
iOS 11.3 Jailbreak
iOS 11.3 is upcoming iOS version. Apple seeded iOS 11.3 beta to the developers. Anzhuang and Velonzy properly work on these iOS 11.3 beta versions. So it can recommend as best jailbreak app installers for iOS 11.3 jailbreak.
However, there is no any jailbreak news about watchOS 4 and higher versions to install Cydia yet. Apple watch jailbreak is very rare when we compare with other Apple devices such as iPhone Jailbreak, iPad Jailbreak and iPod Jailbreak.
OverCl0ck Jailbreak for watchOS 3
OverClock is latest Jailbreak project for watchOS 3. It is developed by the Ben Sparkes who brought us Meridian Jailbreak for iOS 10.X. This Jailbreak tool based on the v0rtex exploit to get root access on the Apple Watch. This method is very similar to Max Bazaliy’s method which was demonstrated at DEF CON 2017.
This is still in early development stage, and Ben Sparkes release it as XCode project to GitHub, because collaboration is necessary to move forward.
Device compatibility -  Apple Watch Series 1
Version Compatibility - 

watchOS 3.0

watchOS 3.1

watchOS 3.1.1

watchOS 3.2

watchOS 3.2.2

watchOS 3.2.3
Important : It has not published IPA yet, If you are a developer, you can download the necessary files using Github. Here is the Official link.
According to developer following functions require development. These functions will be added to the future updates of OverCl0ck Jailbreak tool.
Fix watch_offsetfinder utility to find offsets correctly.
Fix v0rtex exploit.
Add kernel patches
Codesigning patch
Mount root filesystem with full read/write permissions
Add SSH support with Dropbear client
Find reliable way to transfer files to Watch
Port Comex’s Substitute (Substrate alternative) to watchOS 3
Add a Cydia-like package installer for running tweaks

Why should iWatch jailbreak

iWatch (Apple Watch) introduced without some most necessary functions such as Web browsing. Also, Apple limits some of watch face designs to specific Apple Watch models.
Cydia offers many third-party apps to customize the iOS devices as the most popular 3rd party app store for jailbroken devices. Therefore jailbreak is the only option to get those missing functions as jailbreak tweaks to iWatch.
Reasons for iWatch jailbreak
Stock apps customization.
Watch faces changes.
More themes.
Custom elements complications.
Home Screen Customization
iOS 11.2.6/11.2.5 Jailbreak
You can install jailbreak apps to iOS 11.2.6 & iOS 11.2.5 versions using Dev code extraction method or UDID registration method. You can get Dev code extraction method from zJailbreak, Xabsi or iExtras app stores. get the both iOS 11.2.6 & iOS 11.2.5 jailbreak info from here.
Apple Watch Series 2