Windows RT differs greatly from Windows 8. With Windows RT, you can't install any desktop app you want and are limited mostly to the tiled Metro apps. A jailbreak, however, is available now that will free Windows RT tablets (like the Microsoft Surface with Windows RT) so they can act like full-fledged laptops. It's even possible to run Mac OS X Server on them.
The Windows RT jailbreaking tool has been released on XDA Developers. The biggest downside is the jailbreak has to reset every time the device boots. Also, you'll need apps compiled for this jailbreak. VNC server/client, Putty, 7-Zip, and other desktop apps have already been ported to Windows RT, with more likely to be added now that this jailbreak is out.
Perhaps the most interesting hack is the ability to run an OS from Apple on Windows RT. Programmer Steve Troughton-Smith has posted this image of Apple Rhapsody (an early version of OS X Server) running on his jailbroken Windows RT.
The potential for Windows RT is now greater than it ever was before, thankfully. It also means you could buy a less expensive RT tablet and still get the desktop experience you need.