Perhaps it didn't go smoothly, but the Microsoft Exchange team did make the feature-complete Exchange Server 2010 Release Candidate (RC) available for download this week. On Tuesday, Michael Atalla announced the RC's availability on the Exchange Team Blog, but in what seemed like a cruel August Fool's joke, the download link didn't lead to the RC after all. After a few hours, Microsoft sorted out the problem, and all seems to be proceeding fine now.
Along with the Exchange Server 2010 RC release came some additional welcome news. First, the RC will be supported on Windows Server 2008 R2 as well as Server 2008 RTM. So, no problem with Exchange 2010 like they've got with Exchange 2007, anyway. Also, contrary to previous expectations, you will be able to do an in-place upgrade from the RC to the RTM of Exchange 2010. This is a nice move that could encourage companies to be more thorough in their test deployments of the new platform, knowing that they won't necessarily have to rebuild from scratch to move to the finished product.
Finally, Exchange 2010 RC is capable of coexistence with Exchange 2007 and Exchange 2003, which the beta wasn't, so you can get it running to test those real-world mixed environments. Note, however, that you need Exchange 2007 SP2, which hasn't been released yet, for that coexistence scenario. However, Paul Bowden, release manager for Exchange, posted a comment to the original blog post early this morning that states SP2 "will be available early next week." Be on the lookout for that, and be ready for more testing!