Andrew already bookmarked this, but I wanted to add a few more tags and note this looks to be a very promising alternative to Raphael or Processing, as it seems to have good performance and active development.
Wicked awesome gallery of Processing projects. These are all done with the Java version, which is the main difference between this and the Sketchpad site.
Google points out their implementation of OAuth 2.0 is "experimental" but it is a standard and apparently easier to implement, so I think it's the best choice.