Beta 4 for phpBB 3.0 has been released. This time around users of the forum application will find that it also contains something new, an update path.
With this beta an update path is provided, though being not fully supported. We decided to give away the proposed update package to let it properly test and fix any remaining issues encountered before using this as the primary method of updating. This means that you should test the update and report any bugs or issues you notice, but not depend on a successful update - you should still not use this beta in a live environment and you should always be able to completely remove your installation to perform a fresh install.
The current update package, from what I can tell, currently only provides an update from phpBB 3.0 Beta 3 to Beta 4.
The original announcement at phpBB.com comes in two versions; the first posted on the phpBB.com forum and the second posted in the phpBB.com development pages . Downloads are available on the second link.