From Priority Club Rewards press release 10amET, March 29:

New feature:

Last Minute Reward Nights: A hotel industry first, “Last Minute Reward Nights” will allow Priority Club members globally to redeem Reward Nights at a 50% discount off the regular point price, for selected properties. Members will receive an e-mail on Monday providing a list of hotels where this offer will be available the following weekend, Friday, Saturday and Sunday nights. Initially, this program will be offered on the first full weekend of every month, starting with May 6, 7 and 8, 2011.

There does not seem to be any change with Points + Cash rewards:
"6. Priority Club® members have the flexibility to use points or Points & Cash®. Members can choose to redeem Priority Club points for a Reward Night in three ways with Points & Cash: use existing points for the desired Reward Night; use existing points and 5,000 points purchased for US $40 to total the required points; or use existing points and 10,000 points purchased for US $60 to total the required points."