These release schedules are coming after Robbie began tweaking the release schedule for Ubuntu 10.10 (codenamed the Maverick Meerkat) from the original Ubuntu 10.10 release schedule from its final release on the 28th of October. Mark Shuttleworth wants to release Ubuntu 10.10 on the 10th of October (10/10/10), and so that's when the Maverick Meerkat will be introduced to the world.
While these future release schedules are still quite tentative, they are available from the Ubuntu Wiki Release Schedule.
The tentative release schedule for Ubuntu 11.04 puts the first alpha release coming on the 4th of November followed by four more alpha releases, a beta release on the 31st of March, a release candidate on the 21st of April, and then a final release of Ubuntu 11.04 on the 28th of April.
The first alpha release for Ubuntu 11.10 might be out on the 3rd of June -- with just three alpha releases for this cycle -- a beta release on the 2nd of September, a release candidate on the 16th of October next year, and then the final release of Ubuntu 11.10 on the 13th of October in 2011.
Looking two years out, Ubuntu 12.04 LTS should have its first alpha release on the 3rd of November in 2011, the first beta releases on the 23rd of February in 2012, and a final release of Ubuntu 12.04 LTS on the 26th of April. Ubuntu 12.04 is expected to have four alpha releases and two betas.