Just a quick note on this, according to Ross Smith :
" We regret the impact that this delay has on our customers, and as always, we continue to identify ways to better serve your needs through our regular servicing releases.
The release date for Exchange 2013 RTM CU1 is currently planned for April 2nd.
We will let you know if that date changes, as well as, post an announcement when the download is live. "
Read further on :
Exchange 2013 RTM CU1 Status - Exchange Team Blog - Site Home - TechNet Blogshttp://blogs.technet.com/b/exchange/archive/2013/03/25/exchange-2013-rtm-cu1-status.aspx