The MAPI/CDO download package now works on Windows Server 2008 and Vista. The main blocker to getting this to work was the fact that in Windows Server 2008 and Vista, mapi32.dll was marked as a system file. Any attempt to replace it would be blocked or undone. Exchange's MAPI has always replaced mapi32.dll with its own version, so it couldn't work on those operating systems.
The fix is modify Exchange's MAPI to take advantage of the MAPI Stub Library mechanism. We moved Exchange's MAPI binaries out of system32/syswow64 and placed them under C:\Program Files\ExchangeMAPI ("Program Files (x86)" on a 64 bit machine). We also renamed Exchange's mapi32.dll binary. It's now called ExMAPI32.dll.
Update: Looks like the Ehlo blog picked this up. Welcome Ehlo readers! I was involved in getting this update done, so lemme know if you have any questions.
Windows 7 x64 with Outlook 2007 installed;
"Messaging API and Collaboration Data Objects 1.2.1 cannot be installed with Microsoft Outlook"
Same if I try setting compatibility of the installer to anything other than Windows 7.
Steven - this is expected. The MAPICDO package cannot be installed on a machine with Outlook on it. If you wanted CDO there's a different installer for that which includes just CDO.
Just want to repeat Sridhar's question: is there (will there be) a 64 bit MAPICDO release, i.e. being able to talk MAPI to Exchange from a 64 bit program (without using a 64 bit version of Outlook)?
Lars - there are no plans for a 64 bit MAPICDO.