updated 07:30 pm EDT, Fri May 27, 2011
Developer tools and enhanced add-on manager too
Mozilla's development cycle dictates that three generations of its popular web browser Firefox must be in an active cycle. Thus, Firefox 4 is the current mainstream release (currently at 4.0.1), Firefox 5 has recently entered beta, and that means that Firefox 6, known as Aurora, has just begun its development cycle, now offering a rough alpha release for testing and feedback.
Web developers will find that Aurora offers a number of improvements and new features, starting the Scratchpad but extending to improved networking (using a more recent Websockets), support for HTML5 properties such as "progress" and "track," fixes for tags like "canvas" and CSS text attributes, along with other changes detailed here.
A quick run-through of a few sites with Aurora showed plenty of speed, along with plenty of rendering errors, and of course most add-ons, themes and other extras do not work with it.