lubuntu is a faster, more lightweight and energy saving variant of Ubuntu using LXDE, the Lightweight X11 Desktop Environment. The lubuntu team aims to earn official endorsement from Canonical.
* Based on the lightweight LXDE desktop environment.
* Pcmanfm 0.9.8, a fast and lightweight files manager using gio/gvfs.
* Lxdm, a lightweight GTK display manager.
* Chromium, the open-source version of Google Chrome.
* … and, of course, based on Ubuntu 11.04
You can download latest version of lubuntu 11.04 from here
Lubuntu 11.04(Natty) installation video and desktop Video