We'll, I sat the SQL Server 2008 Transition Certification Exam 70-453 back in December 2008 to migrate my SQL Server 2005 MCITP award to SQL Server 2008. This exam is basically both the technical specialist and professional level exams rolled into one examination.
In all honesty, the exam wasn't all that difficult, but did mean spending a fair amount of time getting to grips with new features in SQL Server 2008, as majority of the examination covers familar topics that SQL Server 2005 product includes. Although, where they do differ is on the new features of SQL Server 2008, thus requirement to spend time understanding these new tools.
Good luck to everyone who is scheduled to sit the exam!
Well worth it!