Microsoft has released Microsoft Exchange Server 2010 Service Pack 1 Beta

Microsoft Exchange Server 2010 helps you achieve new levels of reliability and performance by delivering features that help to simplify your administration, protect your communications, and delight your customers by meeting their demands for greater business mobility.

Microsoft Exchange Server 2010 SP1 Beta released

Exchange Web Services Managed API 1.1 Beta has been also released:
Exchange Web Services Managed API 1.1 Beta