Microsoft has now released the the majority of the upgrade exams from SQL Server 2005 to SQL Server 2008.
I see the:
70-453 upgrade from MCITP SQL DBA 2005 to MCITP SQL DBA 2008
70-455 upgrade from MCITP SQL 2005 BI to MCITP SQL 2008 BI
But the 70-454 upgrade from MCITP SQL Dev 2005 to MCITP SQL Dev 2008 hasn’t been released yet.
I’m sure that it will be released soon.
These upgrade exams are a great way to upgrade your certifications as you get both the MCTS and MCITP certifications upgraded with a single certification exam.