There seems to be a concept that no-one should install a new version of SQL Server until at least one service pack has been released for it. I've never ascribed to that thinking. I find it amusing that customers who would not install the RTM version of SQL Server 2008 (which was fully regression tested) would happily run SQL Server 2005 SP2 plus about 10 cumulative updates (which weren't).
Most of the issues I've seen with new versions tends to relate to the newer functionality. You do occasionally find exceptions to this but that's also why you need to do reasonable testing on your own applications.
Regardless, that adoption blocker is now gone with the release today of SP1 for SQL Server 2008. You can find it here: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=66ab3dbb-bf3e-4f46-9559-ccc6a4f9dc19