Ubuntu 11.10, 10.04.4 and 8.04.4 were launched back in October 13, 2011, April 29, 2010 and April 24, 2008 respectively the three distributions have outlived their support period of 18 months, 3 years and 5 years respectively and will no longer receive any updates. Users of these systems would have to inevitably migrate to newer versions they want to ensure that their production systems are upto date in terms of patches and security updates.
Users of Ubuntu 11.10 and 10.04 LTS would be able to opt for a direct 12.04 LTS upgrade through the Update manager. Canonical has recommended that users upgrade to newer systems to keep on receiving updates as well as to stay secure. Users can head on to the upgrade notes for information on how to upgrade their distributions.