I have already heard about this as a rumour in April, and infact it has become reality: 7-11 has turned some of their markets into Kwik-E-Marts:
They even got some of the typical Simpsons products in these stores, like buzz cola and KrustyO’s. A list of these Simpsons-inspired products is over here.
You can find a whole bunch of photos over here at flickr.
However, it sounds like they haven’t done this promotion in every state… You can locate a Kwik-E-Mart near you via this locator…
Oh, and Jet Blue („the official airline of Springfield“) also has a Simpsons tie-in going.