It appears that our run of fairly benign VS SP’s is over… I've now installed the VS 2010 SP1 in a few simple test environments (x64) and all of them are having issues. Add-in failures, failed package loading, missing SQL Intellisense, XAML designer failure, etc. Make sure you test this Service Pack thoroughly before you release it to your production environment. Microsoft Connect is the official repository for issues with Service Pack 1.