Microsoft has now publically released SQL Server 2012 RC0. If you have not downloaded CTP3, go ahead and download RC0 and start getting familiar with it. RC0 should be very stable, so I don’t expect that you will find many or any blocking issues.
You can download RC0 here: http://www.microsoft.com/download/en/details.aspx?id=28145
For detailed information an what is new in RC0, see the TechNet article here: http://social.technet.microsoft.com/wiki/contents/articles/3783.aspx