I want to draw your attention to the following announcement on Microsoft DPM, further details can be found here and the BETA1 version can be downloaded from here. Why is this important for Exchange..? Well it is supported with Exchange 2007 and can be used to facilitate your HA strategy.
"DPM offers integrated support for Exchange Servers 2003 and 2007 with advanced cluster configurations, shorter SQL Server backup windows without the need for compression, and integrated restores for SharePoint. DPM also provides one touch application restores with zero data loss."
This is a technology that we have been crying out for. The FAQ is here