I installed a customer with Exchange 2003 SP2 last week. They already had SP2 installed when I showed up to install their new CallManager and Unity systems, so I didn't really get a choice in the matter. We used Unity 4.1(1), and I installed the SP2 update to the local Exchange administration tools, and went on with life. We didn't do anything above and beyond what we were asked to do by the Permissions Wizard and the associated documentation that tells you what to set with Exchange System Manager.
Unity seems to be functioning fine for them with one minor caveat. They're running into a problem that exactly matches the one described in CSCsc21517, but we obtained ES11 from TAC and applied that, and it did not seem to fix the problem. We had to use AST to undo the receipt message filtering; we usually enable it as part of all our UM installs to avoid user complaints. If you're not enabling receipt filtering, it's a nonissue for you, and I don't know if this has anything to do with Exchange SP2. We're still running the TAC case on that one.
