[Osiris]

The next beta of Firefox 3 has been uploaded to the Mozilla ftp site and is currently distributed to all mirror websites to ensure speedy downloads when the announcement is made on the official website. You can already grab it from several mirrors so if you want to avoid slow connections and downloads to the server once everyone starts downloading it.
The official release notes to not state what has been updated and changed in this new release but there will surely be an announcement soon about this. The new release is entitled release candidate as well.
I did discover only one new improvement so far that was announced on the gemal blog. It stated that Firefox 3 beta 5 will have improved connection parallelism. What this means is a increase in simultaneous connections which should make Firefox even faster if you have not altered the settings yet.

Firefox 3 Beta 5 has been released

[Mak213]

Have to check and see if it is on auto updates later.