I have been waiting for this day. I am sure some of you were too!
The Release Candidate for Exchange Server 2010 has been announced and is available for download on Technet. You can download it here.
Exchange 2010 brings unparalleled productivity enhancements, availability features and cost savings. You can read more about new features introduced in Exchange Server 2010 here.
Update: The download link is live now. I still could not find it on MSDN subscriber downloads. Download it from link above.