DAG in Exchange Server 2010
I've just read In the UC blog an entry where the UC team states that DAG will be supported on Exchange Server 2010 Standard Edition. Isn't that cool? :)
On the server side, Exchange Server Standard will now support high availability, so all customers can take full advantage of the new database availability group capabilities. Exchange Server Enterprise enables configurations with up to 100 databases per server.
Read more at source: http://blogs.technet.com/uc/archive/2009/10/27/exchange-2010-revving-the-engines-for-launch.aspx