Since several people have PM'd me about it, here is my port of MikTeX 2.9 for Windows RT. I've been out with the flu and ... I'll be rather busy this week, so I won't have much time to support it, but basically extract into your program files directory and run MikTeX-TexWorks.exe in the miktex\bin\arm directory. You might have to perform some configuration.... I haven't had the chance to figure out what those steps are from clean install, but it might involve running initexmf and having it initialize the file cache.