Microsoft announced new features in Silverlight 2. One of the most exciting new features is DeepZoom. This capability allows users to explore collections of super high resolution imagery, from a 2 or 3 megapixel shot from a digital camera to gigapixel scans of museum pieces, all without waiting for huge file downloads. Deep Zoom is based on the same Seadragon technology that you have seen in our demos and in the Photosynth preview.
PhotoZoom is an experimental project developed by a small group of Microsoft developers, and it is definitely not an official, supported Microsoft product. PhotoZoom is a web site where anyone can upload their photos and turn them into zoom-able, pan-able albums, using the Deep Zoom technology in Silverlight 2 Beta 1.
Link: WinVistaClub Article