I'm just coming back from MS beta exam 71-448 (TS: Microsoft SQL Server 2008, Business Intelligence Development and Maintenance). There were too many questions (70!) and the time was around 3 hours which was more than enough.
It was a bit disappointing that not many questions were specifically related to SQL Server 2008 new features -not even 5 questions were specific to that!- so if you don't know much about the new features, don't worry!
SSAS: · many admin tasks · a few MDX · dimension settings · attribute properties · performance monitoring and tuning · using profiler for monitoring user roles · cube processing options · deployment options · setting permission
SSRS: · security · backup the SSRS database · setting parameters · assembly file · custom control · failover environment
SSIS: · a few questions around SSIS package configuration · transaction · a couple of Foreach loop (file)
Data Mining: · a few DMX questions
In total it was not tough if you have passed the 70-445 (SQL 2005) exam, you just need to review the topics from Microsoft website and play around the topics that you haven’t had chance to work on them.
Good luck!