Food for thought - http://www.ted.com/index.php/talks/view/id/129 is rather interesting software in its own right, which appears (to me, at least) to lend itself well to multitouch interaction.

I worked on the university project that Photosynth was based on (Photo Tourism http://phototour.cs.washington.edu), and I was thinking of building a multitouch interface for it.

I think “Seadragon” is now called “Deep Zoom” and you can implement in your own WPF and Silverlight apps now.

Deep Zoom Demo : http://memorabilia.hardrock.com/

Deep Zoom Composer (from M$) : http://www.microsoft.com/downloads/details.aspx?FamilyID=457B17B7-52BF-4BDA-87A3-FA8A4673F8BF&displaylang=en