Ok, I'm surprised that no one is reporting this on the blogs I typically follow, but it is my understanding that my local Kmart (Durham, near South Square - between the Target and the Harris Teeter shopping centers) is participating.
Kmart is doubling coupons up to and INCLUDING $2 from 4/4 through 4/10. That means up to $4 off. They are only doubling up to 5 coupons per day. Here's a great deals list from Southern Savers.