The next ubuntu stable version is going to be released on 23rd April 2009.If you want to order your free CDS use the following link

https://shipit.ubuntu.com/

If you want to know new features in ubuntu 9.04 as follows

* Linux kernel version 2.6.28

* A new notification system

* Faster boot times

* GNOME 2.26 desktop environment

* Community desktop themes and brand new artwork

* Evolutionary EXT4 filesystem

* Support for many new devices (wireless, webcams, mobile phones, etc.)