The jQuery UI team needs your help in ensuring that jQuery UI v1.5 is rock solid. So they're conducting a Worldwide Sprint in order to get as much help as possible and get jQuery UI launched.
“The jQuery UI Team is pleased to announce its first Worldwide Sprint, to take place next Friday and Saturday, March 14-15, 2008. Two full days of testing, fixes, documentation, and general getting-stuff-done. Our goal is to get the jQuery UI 1.5 release (alpha, beta) ready for final, and we invite any and all to help. Whether you have an hour, or an afternoon, come and run really fast with us.”
Details of the sprint can be found here with specifics on how you can help: