Sugar is the graphical user interface originally developed for the One Laptop per Child computer/education project and as of May 2008 being developed under the umbrella of Sugar Labs.
Sugar is used on the OLPC XO-1 laptop computer and is also available as a session option on Debian, Ubuntu and Fedora. Unlike more traditional desktop environments, it does not use a "desktop" metaphor and only focuses on one task at a time.
Main contributors to the project include Christopher Blizzard and Marco Pesenti Gritti, Eben Eliason, Tomeu Vizoso, Simon Schampijer, Dan Williams, Walter Bender, Christian Schmidt, Lisa Strausfeld, and Takaaki Okada. The free software community has also contributed greatly to Sugar. Released under the GNU GPL, Sugar is free software.
It is written in the interpreted Python programming language, whereas most other environments are written in a compiled language such as C. Sugar is also referred to as the OLPC Python Environment. It is composed of the Python language, GTK GUI and Gecko HTML engine.
If you want to get involved with it, search by Sugar Group!