Hey guys, I thought I'd add a little of my experience so far here... As you're already aware, RT won't join a domain, but it doesn't meant that some of the normal "Pro" features don't work... You just need to do some manual tweaking. You can create symlinks in order to get your network docs, pics and videos to work perfectly in the "Libraries" part, and thus make the RT think you have all the media locally. It does cause some time-out errors in the logs, but no actual issues. It caches your domain passwords without issue, and assuming you have decent WiFi speed, H.264 mp4's play perfectly fine without stutter from media and network shares. I personally prefer the symlink/native file share access method to media sharing, as it appears to perform fatster, and the metro apps don't seem to have issue. In case it hasn't been covered, here's how:

From here (not RT specific, but the steps work flawlessly)

You need to be in the desktop... Then browse to your server share (I usually use the &Run dialogue box, and type \\server\share) enter and save your domain or share credentials... Then do the following:

Add a non-indexed UNC as a library
===========================
1. Create a folder on your hard drive for shares. i.e. c:\share
2. Create another folder in the above share. i.e. c:\share\music
2. Link the Library to this folder.
3. Delete the folder.
4. Use the mklink in an elevated command prompt to make a symbolic link. Name the link the same as the folder you created above.
i.e - mklink /d c:\share\music \\server\music
5. Done. Now you have non-indexed UNC path as a library.

You'll find that the music and video players both treat the files as local and simply perform faster.

My next step is to see if I can get a logon script running that'll map drives...

Hope it helps.