I check back at your link this AM & found that the "Windows 7 User Experience" video is up now.
I really like that one.
I never tagged my photos but after seeing what win7 does compared to Vista, I'm definitely going to start using that feature too.
Really nice that Win7 gives one a 3D view of the sorted photos instead of the flat view as in Vista.
Many new new features are demoed by these two English guys.
Edit: here is a link to the James O'Neill's blog
(one of the speakers) that refers to his blog for more info.
Edit2: Here is a example of Win7 arranged the photos by tag