I had to do a triple-take on this one. Microsoft Labs has released what they call a tech preview to the iTunes App Store called Seadragon Mobile. Yes, really, Microsoft has released an application for the iPhone.
Seadragon Mobile is an image viewer for large images or a large number of images. The ability to browse hundreds of images in it's collections and zoom into those images to an impressive level of detail is fantastic. Standard pinch-zoom is used to zoom in and out and a slideshow function is available when viewing a collection. Forgetting the Microsoft source, this is a really good image viewer for this kind of content. And except for a few server issues we've had, the app responds really quickly considering the amount of data it is referencing.
Some of the collections available to view include some from Library of Congress, world maps, large scale artwork, and items from Microsoft's Photosynth. Also included is the ability to add your own content from uploaded material at Photosynth, RSS image feeds such as Flickr feeds, and Deep Zoom Content.
Seadragon Mobile is impressive for what it does and it's an interesting demo to play around with. But I have to wonder about it's future.