Sun launched its Identity Server this week, which is positioned as the first component of the Liberty Alliance single sign-on scheme for web site authentication. When the Liberty Alliance was first announced, it seemed that its position was hopeless, as Microsoft Passport and AOL SNS already had their systems implemented and deployed. However, Passport and SNS have not by any means become pervasive, with this months survey finding fewer than 100 unique sites using these systems and Liberty now seems to have a plausible chance to compete with the established systems.