Originally Posted by
jasonvr
Incorrect. See here:
http://hhonors1.hilton.com/en_US/hh/about/diamond.do
(bolding is mine). If you are more than 48 hours out, a reward stay is guaranteed, even for sold out hotels, except for extraordinary demand dates and several "special" properties (listed in the T&C, like the Maldives and Seychelles).
Actually, newbluesea was correct until April 1, 2011. The DSR was not specifically stated previously for reward reservations.
What you quote is from the newly revised Hhonors T&C.