Network World reports from Microsoft TechEd: http://www.networkworld.com/news/2009/051409-microsoft-teched.html?page=2
"At TechEd, keynote presenter Bill Veghte, senior vice president for the Windows business, said companies testing Vista should stop and move to testing Windows 7. The same advice was repeated for users who have not yet moved to Exchange 2007; they were told to skip it and wait for 2010."
I like the guidance. So dear customer. Don't upgrade now. Keep paying every year on the Microsoft Enterprise Agreement. And when 2010 comes, hopefully in 2010, then spend lot more money again, and hopefully upgrade...
Yet another reason for Customers to NOT renew Microsoft Enterprise Agreement and consider Microsoft alternatives.
Wait till 2010 (i guess 2011) for any upgrades says Microsoft