There are two practice tests available for the Configuring Groove exam 70-555 from two providers, one from Selftest engine and another (allegedly since it isn't yet listed in their catalog yet) from MeasureUp.  

A new collection of online courses is available. This material prepares people for Exam 70-555, Configuring Microsoft Office Groove 2007 Collection 6452: Implementing Microsoft® Office Groove® Server 2007 In this 12 hour on-line collection, IT Professionals will learn how to Implement, Configure and Manage Microsoft Office Groove 2007. ...