SuperSite for Windows published a review on Exchange Server 2007 Beta 2

Developed in tandem with Office 2007/Outlook 2007 and a future version of Windows Mobile, Exchange Server 2007 will be the biggest upgrade to Microsoft's email and messaging server yet. At a basic level, Exchange has been rearchitected to be more componentized, like Longhorn Server and Windows Vista, and Exchange 2007 deployments will be roles-based as a result, and more secure thanks to role interdependency minimization. It will manage PBX voice mail, VoIP phone calls, and fax messages in addition to email. It will include pervasive security features and technologies, and integrate with a new line of ForeFront security products. It will feature a brand new management interface in which the graphical tools are built on top of a Monad-derived command line environment, like a UNIX server. And it will require 64-bit x64-based server hardware, a break with the 32-bit past that has riled some Exchange customers. Nope, this isn't your father's Exchange. And I like what I see, very much so.

Exchange Server 2007 Beta 2 Review