Sciforma PSNext (http://www.sciforma.com/page?id=316) is a collaborative planning software to be compared to Primavera PM.
PSNext is 100% Java, when Primavera PM is mainly a server - client application.
PSNext is not as huge projects oriented as Primavera PM, it is much more a middle size projects planning software, rather easy to use, both for a planner or an administrator.
PSNext is #2 to MS Project Server in France