Trika blogged about a Microsoft Pilot program that will instead of a simulation will have a Performance based engine by using a virtual Server 2008 emulation. I am very excited about this and have already signed up at Prometric to take the exam (70-113: TS: Windows® Server 2008 Active Directory, Configuring) on August 7th. The bad news of course is that this is NOT a beta, only a pilot so the exam counts as nothing and will not be on my transcript even if I passed. Thats ok though, because I want to get hands on with the technology to see where things are going. Plus if your one of the first 3000 who take it, you will receive an exam voucher.
Get all the information at Trika’s blog: http://blogs.msdn.com/trika/archive/2008/07/31/performance-based-testing-pilot.aspx

