Just a reminder, recently posted from mdz@ubuntu – the 4.10 release, Warty Warthog, is about to officially end-of-life.
As of the 30th of April, 2006, there will be no further security updates for this version. See https://lists.ubuntu.com/archives/ubuntu-announce/2006-March/000061.html for more details.
Theoretically, the wider community could choose to support this version, and retrofit security changes. In practice, I don't think it's likely to happen. It was the very first Ubuntu version to be released, and an upgrade is strongly recommended.
The next version of Ubuntu, Dapper Drake, will be released on the 1st of June 2006. This version will be officially supported for 5 years on the server, and 3 years on the desktop. It's a little late – it should have been released on the 20th of April 2006, but the edlay was put in place for clear reasons. See https://lists.ubuntu.com/archives/ubuntu-announce/2006-March/000058.html for more details.