Mozilla released an early alpha version of Firefox 3.0, it's codenamed Gran Paradiso and it's made available for testing purposes only.
New Page Info window
any Cocoa user interface improvements and bug fixes
Basic Mac OS X crash reporting via Breakpad
Improvements to offline application support. Enabled Listing of Offline Resources and implemented SQL device for the offline cache. See Marking Resources for Offline Use for further details on offline support.
Miscellaneous Gecko 1.9 bug fixes
Web application developers can download it over here.