Exchange Server 2010 SP1 Beta incorporates a number of feature updates including: archiving and discovery enhancements, a faster Outlook Web App (OWA), upgraded mobility features, and several improvements in the management UI. The SP1 beta is available to the public and can be downloaded

http://www.microsoft.com/downloads/details.aspx?FamilyID=a0965fc9-2723-4947-ae6b-74bc3808e72a&displaylang=en