Today Mircosoft released its first rollup (RU1)  for Exchange 2010 http://www.microsoft.com/downloads/details.aspx?FamilyID=371add31-d7a0-4c8b-8325-a6fced2d05e6&displaylang=en 
One of the biggest advantages to RU1 is allowing functionality with RIMs BES servers, however RIM is suppose to release an MR1 soon for Exchange 2010 intergration that will be required on the BES servers
Changes http://support.microsoft.com/?kbid=976573
 
RIM information to configure Exchange 2010 and BES
http://na.blackberry.com/eng/services/server/exchange/2010support.jsp