Project Server 2013
Project Server 2010
Our User Assistance stars have just posted some brand new content to help new users to Project Online. The new Project Online getting started articles can be found at http://office.microsoft.com/en-us/project-server-help/get-started-with-project-online-HA102858793.aspx and walks you through the Project Online sign-up, adding your people and creating projects. Thanks Sonia and all the folks in the review cycle who helped make this happen!
*** Update 10/6/2014 - new link http://aka.ms/ProjectOnlineGetStarted and the page doesn't look quite like that any more... ***