I don't know for sure if it uses the same format as WMV but the fact that I'm not getting any tags says to me that they don't. Unless of course I need to do something more than just import the files to get it to happen.
Update library from tags won't bring in this metadata either, I've tried for years, but just can't get this info into MC. As you say, with the focus now on TV, maybe this can change soon. It's still MUCH easier for the wife to use WMC, so we're stuck with it for recording her stuff for now, still.
**Oh, forgot to mention, one option is to run the wtv files thru the process I wrote up for commercial skipping. this will give you a .ts version of the program, and an .edl file, which MC will use, giving you the metadata you want, and hands-free commercial skipping. if you don't want to keep the .wtv file, the process can delete this original file also for you.
http://yabb.jriver.com/interact/index.php?topic=67579.0