Sloppy Documentation (HMC 4.x)
At work, I have a project that has been going on for a month or two. It originally started out as replacing our Hosted Exchange 2003 environment with a new fancy Exchange 2007 environment and add on extra features. To provision this, we have decided to abandon our own provisioning system due to various issues with documentation (or lack there of it) from Microsoft. So, we have decided to drink the Kool-Aid and are rolling with their HMC (Hosted Messaging and Collaboration).