“Our Volume License customers with active Software Assurance (SA) on these productswill be one of the first to receive the 2010 set of products. They will be able to download the products in English via the Volume Licensing Service Center starting April 27. Customers without SA will be able to purchase the new products through Volume Licensing from Microsoft partners starting May 1.”
Read more at blogs.technet.com/office2010/archive/2010/04/15/office-2010-reaches-rtm.aspx