I just noticed that TQ posted a sample VSTO 2005 SE add-in for Outlook 2007 that implements form region handling. I know a number of developers in the Outlook community have been looking for a good sample on how to build a VSTO add-in that uses form regions since simply implementing FormRegionStartup on the ThisAddin class doesn't work. If you are struggling to figure out how to make this work, I'd encourage you to go over and take a look at his sample and implementation notes.