For Windows 8.0/8.1 RT, another jailbreak exists thanks to Myriachan from XDA. You can find this jailbreak in the repo, or you can find on XDA -- http://forum.
To jailbreak your Windows RT device, just follow the instructions in the thread -- download the .zip file, extract it, and double-click the runExploit.bat file.
Windows RT 8.1 Update includes improvements to make Windows more familiar and convenient for using touch and mouse input with Surface. If you're running Windows ...
An all-in-on package for Tegra based Windows RT tablets (ASUS VivoTab RT, Lenovo IdeaPad Yoga 11, Microsoft Surface RT & Microsoft Surface 2) Extract · Disabling Secure Boot · Windows Configuration · Jailbreak Killing Updates
I made this guide with my experience on jailbreaking the surface rt, 1 and 2 (i have a lot of them, lol) and i hope this helps someone jailbreaking theirs.