This one rocked. Ryan talks about it here: http://blogs.msdn.com/stoey/archive/2008/03/05/mix08-silverlight-2-deep-zoom-live-at-hard-rock-memorabilia-site.aspx
There was an astounding demo during the Mix08 keynote this morning showcasing Silverlight "Deep Zoom" technology. The best part is you can check it out for yourself right now. Head over to the Hard Rock Memorabilia site and you'll have to install Silverlight 2 (only takes a moment).
Then you'll see this page with a few hundred high resolution photos from the Hard Rock memorabilia collection. Simply use your mouse to zoom in. I mean REALLY zoom in...
Check it out:
The main page where you can just zoom and fly around to various photos: