Just a few links where you can find more info about SQL Server 2008 Certification in general and about the separate certification tracks and exams.
MCTS: SQL Server 2008, Implementation and Maintenance
MCTS: SQL Server 2008, Database Development
MCTS: SQL Server 2008, Business Intelligence Development and Maintenance
MCITP: Database Administrator 2008
MCITP: Database Developer 2008
MCITP: Business Intelligence Developer 2008