Canonical announced the second maintenance release of Ubuntu 6.06 LTS which is including several Security Fixes and some extra Hardware Support for servers.
Ubuntu 6.06 LTS has the longest support period until June 2009 for Desktop Users and June 2011 for Server Usages.
By the way, if you already installed Ubuntu 6.06 LTS, you don't need to download the newer version. All you should do is to run "sudo apt-get update" and "sudo apt-get upgrade", and you will have the newer version.

The Ubuntu team announced Ubuntu 6.06 LTS, codenamed "Dapper Drake".
This release includes both installable Desktop CDs and alternate text-mode installation CDs for several architectures, for Ubuntu, Kubuntu and Edubuntu.
Ubuntu 6.06 LTS will be the first Ubuntu release with a long-term support cycle: free security updates and commercial technical support will be available for three years on the desktop, and five years on the server.
For Downloading this distribution you can follow this Link.