This is the same source code that's available for download on Microsoft's Expression Gallery:
Please note that Seadragon Ajax is no longer under active development or maintenance, and has not been since February 2011. It works fine in its current form, but is lacking some potentially useful features, most notably touch support and hardware acceleration on mobile devices.
Unfortunately, this codebase was never fully open-sourced — it was released by Microsoft under a custom license — so continued development of this codebase is unappealing and unlikely.
However, there is a fork of this library called OpenSeadragon that has started gaining popularity, and this fork is under active development and maintenance — including by @iangilman, author of the original Seadragon Ajax prototypes! Check it out:
If you still choose to use this version of Seadragon Ajax, you can find open community support and discussion at: