This probably wont work with reward stays but I'm going to try anyway. I hope this isnt all they are offering for Q3 2013
Stay for two consecutive weekend nights (Friday, Saturday or Sunday) and get a $50 Vacation Pay Prepaid MasterCard (up to $200) when you pay for your stay with a MasterCard card.
Here is the link to sign up
This is mail in promotion so there is a bit of extra hassle. I did a similar promotion last year for $75 and they sent me a gift card fairly quickly.
Book and complete a qualifying
stay at any hotel in the IHG®
family of brands and pay with your
MasterCard card between
May 31, 2013 and September 1, 2013.