I've noticed that Publix has been selling some really nicely marbled beef lately; particularly the porterhouse steaks. Yesterday I spotted these "NY" strip steaks, which are clearly prime beef.
What's happening is that the market for prime beef has shrunk considerably; there was a time when all of the prime beef went to restaurants, but now restaurants are using gimmicks to sell lower grade cuts. It's a tough sell to get people to pay the $21.95/lb they try to get for prime filet at publix; I always wonder who is paying that price? You might as well go out to eat. So what happens is that often supermarkets are getting much better cuts of beef as part of their bulk purchases.
Supermarkets usually sell "Choice" grade meat; and it's usually pretty lean. But lately they've been getting some better stuff. Luckily, most people think that marbling is bad; I regularly see people picking up the reddest looking meat; but marbling is good. Just don't mistake a big chunk of fat on the side for marbling; you want the fat to be nicely veined throughout the meat.
I cooked one of these babies up on my Foreman Grill at the highest setting and it was one of the best strip steaks I've had in a while.