At the last Ubuntu Developer Summit, the Ubuntu Server team discussed moving to a fixed cadence for releasing point releases of OpenStack into Ubuntu and the Ubuntu Cloud Archive for 12.04 under the Ubuntu Stable Release update process.
The amount of time between upstream point release and acceptance into Ubuntu and the Ubuntu Cloud Archive is relatively short, but the team felt that a more regular cadence was required to allow users of OpenStack on Ubuntu to plan around upstream point releases.
For future OpenStack point releases the Ubuntu Server team will be following a new cadence for pushing these releases into Ubuntu. This should allow the team to test and promote a point release of OpenStack into Ubuntu within two weeks of the upstream point release. Hopefully this will allow users of OpenStack on Ubuntu to plan upgrades a little more effectively going fowards.
For full details see the SRU Cadence documentation.