As you probably know, BlackBerry Enterprise Server (BES) is not compatible with Microsoft Exchange Server 2010. If you’re a fan of this product, the good news is that by the end of year, Blackberry will have the new version ready.
“October 20, 2009 – Research In Motion (RIM) is pleased to notify you that we are working in close collaboration with Microsoft on compatibility and support for BlackBerry® Enterprise Server for Microsoft® Exchange Server 2010. Compatibility is expected later this year. BlackBerry® Technical Support Services for BlackBerry Enterprise Server for Microsoft Exchange Server 2010 is expected within 30 days following the global availability of Microsoft Exchange Server 2010.”
Source: http://na.blackberry.com/eng/support/software/server_compatibility.jsp#tab_tab_news