Segundo o blog "Born to Learn"  os exames do Windows Server 2008 irão sofrer um update para cobrir as tecnologias do Windows Server 2008 R2. Por enquanto apenas o exame 70-640 será atualizado em setembro.
Bom é só ficar atento ao guia de preparação do exame: TS: Windows Server 2008 Active Directory, Configuring http://goo.gl/3LVp

"FYI - the 70-640 exam has been updated to include R2 content. Other Windows Server 2008 exams also either include content now or will in the near future. The 70-640 prep guide update has been submitted to www.microsoft.com/learning and should go live tomorrow and the rest of the prep guides around Wed, September 1. "

Ben Watson
Director, Training & Certification
Microsoft Learning"

Fonte:http://borntolearn.mslearn.net/forums/tnc/f/18/p/20893/57867.aspx#57867