Last week I got the results of those beta exams (71-448, 71-452) and surprisingly, I passed both!
The surprise was because I passed them though I hadn't had a chance to work with SQL Server 2008 in a real project before, and that means there is something wrong with the exams that you can pass them based on your SQL Server 2005 experience and just reading about new features of the 2008 version.
But the good thing is that I've passed them and there is nothing to worry about till the next version! The next version of SQL Server code-named "Killimanjaro", will be released in the first half of 2010, according to Microsoft officials. The first tech preview test builds of Kilimanjaro are due in the first half of 2009. It will provide the foundation for Microsoft's first data warehouse appliance, code-named Madison, and a BI tool called Gemini that's being designed to bring a broader range of employees into the BI fold.