While we have been talking about Ubuntu 9.10 for months, among the new features on the desktop side is the Ubuntu Software Center (formerly known as the Ubuntu Software Store), a brand new boot experience, a revised theme, the desktop has been updated against GNOME 2.28, and its shipping with the Linux 2.6.31 kernel. On the server side of Ubuntu 9.10 is cloud computing support, AppArmor profiles by default, UEC and EC2 server images, and many other new improvements.
There are also many other improvements to Ubuntu 9.10 and others in the Ubuntu family like Kubuntu and Mythbuntu too, which is briefly described in the Ubuntu 9.10 RC release announcement. The final release of Ubuntu 9.10 is expected on the 29th of October. Succeeding Ubuntu 9.10 will be Ubuntu 10.04 LTS next year, which is codenamed the Lucid Lynx.