I'm calling BS here. So called "enterprise compatibility" is a moving target created by IT guys who don't know what they are doing.We recently upgrade from Exchange 2003 to 2010. Snow Leopard and Lion both are out-of-the-box compatible with the Exchange Web Services protocol introduced with 2007. Our IT folks deliberately reconfigured Exchange so as not to work with either Apple Mail or MS Outlook 2011. Then they turn around and blame the Mac for not being compatible.