Development release
The current development release is codenamed Essex, and scheduled for final release in the spring of 2012.
EssexReleaseSchedule has the detailed dates for this release cycle
The ReleaseCycle explained
Previous releases
2011.3 (Diablo)
Released on Sep 22, 2011 (see DiabloReleaseSchedule)
OpenStack Compute (Nova) 2011.3: https://launchpad.net/nova/diablo/2011.3
OpenStack Image Registry/Delivery (Glance) 2011.3: https://launchpad.net/glance/diablo/2011.3
OpenStack Object Storage (Swift) 1.4.3: https://launchpad.net/swift/diablo/1.4.3
2011.2 (Cactus)
Released on Apr 15, 2011 (see CactusReleaseSchedule)
OpenStack Compute (Nova) 2011.2: https://launchpad.net/nova/cactus/2011.2
OpenStack Image Registry/Delivery (Glance) 2011.2: https://launchpad.net/glance/cactus/2011.2
OpenStack Object Storage (Swift) 1.3.0: https://launchpad.net/swift/1.3/1.3.0
2011.1 (Bexar)
Released on Feb 3, 2011 (see BexarReleaseSchedule)
OpenStack Compute (Nova) 2011.1: https://launchpad.net/nova/bexar/2011.1
OpenStack Image Registry/Delivery (Glance) 0.1.7: https://launchpad.net/glance/bexar/0.1.7
OpenStack Object Storage (Swift) 1.2.0: https://launchpad.net/swift/1.2/1.2.0
2010.1 (Austin)
Released on Oct 21, 2010 (see AustinReleaseSchedule)
OpenStack Compute (Nova) 2010.1: http://launchpad.net/nova/austin/2010.1
OpenStack Object Storage (Swift) 1.1.0: http://launchpad.net/swift/austin/2010.1