@Ian2: No problem, I don't have an RT tablet and only run VS2012 on Win8, so I didn't really have the authority to answer (though I would've guessed the right answer anyway).

Touch+hold has been the touch gesture for right click as far back as the old Windows Mobile OSes (when it was still called PocketPC). It doesn't apply on metro because all right-clicking accomplishes there is showing the app bar, which you get by touch by swiping from the bottom (iirc).