What's special in Exchange Server 2007 SP1?

This article is for all Exchange users. When we work with our customers, they eagerly want to know differences, new features, comparisons, what were its new and special features, product reviews or comprehension information about Exchange Server 2007,

Please find the two useful article, which talks about 'end-to-end' richfull features related information:

Review the features of Exchange Server 2007 including SP1

Comprehensive information on Exchange Server 2007 with SP1