So due to a bunch of weird circumstances, I actually paid my credit card bill over the phone, and even paid through a rep for free.
To make a long story short, the rep told me that I could get 1.5 miles per dollar spent on my CITIAAdvantage MC through January sometime.
She said it was targeted, but YMMV, and you may also have missed the postcard like I did.
She also said that it works for the AMEX.
Post back to let us know if it works for you, and for which cards.
P.S. I hope I didn't miss this on the forums; I did do a quick search to see if it popped up, and I didn't find anything.