Firefox has released the last alpha version 6.0 of Firefox 3 for the testing, it is only recommended for developers and individuals who are ready to mess up their PC. The Firefox Alpha 6 Release Notes have more information and download links. The working name of Firefox 3 is Gran Paradiso

The new features in this development milestone of Mozilla Firefox 3 include an upgraded SQLite engine, improved cookie performance, support for site-specific text size preference and various Gecko 1.9 bug fixes. SQLite Engine is the  database that works as storage for “Places”, which is the new manager for history and bookmarks. Since the bookmarks now run on “Places” they aren’t compatible with Firefox 2. If you add any new bookmarks to Firefox 2, you have to manually import the bookmarks to “Places”.

According to the Mozilla’s schedule, the first beta version of Firefox 3 will be ready by July 31st, the second in September and the final beta release in October. The date of the final release of Firefox version 3 is not decided yet.