Remember this post 46 New Dynamic Management Views In SQL Server 2008 CTP6?
I just checked SQL Server 2008 RC0 and there are no new Dynamic Management Views when compared to CTP6.
Sorry, can't make up any DMVs :-(
Now, if you could do this
SELECT CAST('00:15:00' as TIME(0)) + 5
SELECT DATEADD(hh,5,CAST('00:15:00' as TIME(0)))
Wouldn't that be nice? You can do it with datetime, for example SELECT GETDATE() + 5