If it's an optional I'm all for it. In fact, if they'd extend the thing to not just simple menus but actual little "widgets" (whatever you'd want to call it), some little extensions that can do basic things besides a menu and it would be even more of a tasty option. Preview videos, view a changelog or edit a Subversion commit, toggle things on or off, etc etc.. lends itself to all sorts of possibilities. Put that RT stuff to good use.
It could be something Microsoft could look into opening up for custom entries. It would certainly eliminate the amount of white space currently on the slide out.