Wow, just spotted this amazing solution utilising Windows 7 Touch and Silverlight 3 with Deepzoom.
Check out http://rubrik.ch.msn.com/reportagen/zermatt.aspx and click on the Info button and read how it was created, stunning!!
Yes, it works with a mouse too if you don't have Windows 7 with a Touch display (or for that matter Windows 7), but yeah, the experience is not as immersive!!
Check out the Windows 7 Training kit if you want to build amazing stuff too!!