Firefox 3.6 released, new features added
Today Firefox 3.6 was released, knocking Firefox 2 out of the "Far past". New features since 3.5 (that appear on WCIU) include support for: CSS3 Multiple backgrounds, the File API, CSS Gradients and the WOFF font format.
In addition to the newly added File API feature, I've also added the Web Sockets API. Still an editor's draft so considered "unofficial", but supported in Chrome 4.