Technologically, I wonder how Microsoft Live Labs: Photosynth compares with QuickTime VR?
But socially this could be a very big deal.
I've always found QTVR really worked in web-pages, but I've never seen Apple push it. I guess MS are going to produce something that mixes Flickr's socialization of online photo-collections with online tools for making interactive panoramas and letting you hyperlink between them.
Are panoramas going to be the first media that MS will lead the socialization of?
Update : it is technologically an advance on QTVR. But I'm not sure how important that is. It's the social linking of photos to make a space that's important. Whether you use clever algorithms or human tagging for that is probably less important.
Update 2 : I guess if they took some tips from Croquet it could be the new Windows :-)