Latest Stable released
phpBB3 3.0.10 on January 1, 2011
Download available at
http://www.phpbb.com/downloads/
Changelog :
http://www.phpbb.com/support/documents.php?mode=changelog&version=3
Latest Preview released
phpBB 3.0.9 released on Jul 10, 2011
Official Announcement :
http://www.phpbb.com/community/viewtopic.php?f=14&t=2134142