If Firefox 1.0.5 doesn’t interest you, Deer Park Alpha 2 (Firefox 1.1) is now available for testing. The main changes over Alpha 1 are;

# Software update system to streamline product upgrades (currently disabled)
# Faster browser navigation with improvements to back and forward button performance
# Drag & drop reordering for browser tabs
# Improvements to popup blocking
# Better support for Mac OS X (10.2 & greater)
# Several security enhancements

The Burning Edge has a more complete changelog. The new Auto-Update feature will apparently be tested over the following weeks. Instead of needing to download a whole new setup, this will allow users to download only the component that needs to be updated. This will significantly reduce the size of updates, not to mention the speed up the installation process, i.e. no more downloading a 5MB file, uninstalling & installing the new release.