Jolicloud is "an Internet operating system", based on Ubuntu. Originally aimed at netbooks, the release announcement of Version 1.1, on 7 December 2010, said that "The new focus of the OS is about recycling computers."
Jolicloud is reportedly being tested and optimized to work on the XO. (Some features/apps may only work on the 1.5; updates to come.)
In August 2010, a user on the Jolicloud Forums asked if the OS would work on an OLPC XO-1. The response from an Official Rep was "Maybe in the future, but for now it is not supported."