This link will take you to an article on a new burger/hot dog/ice cream stand in Center City Philadelphia's Franklin Square. As the article indicates, it's clearly modeled after Shake Shack in NYC, although they have regular ice cream instead of frozen custard. http://www.philly.com/philly/restaurants/20090719_Juicy_burger_is_icing_on_cake.html
I just tried it out for myself. The burger was very good. They are about a quarter pound of what appeared to be fresh ground beef. They're served on potato buns and come with onions, pickles, ketchup and mustard. My burger was juice and perfectly cooked (nicely pink inside). I also tried their "Philly hot dog," which is a Kosher dog wrapped in Kosher salami with onions, pickles, tomatoes, peppers and mustard. It was nice, but I'll probably just go for the burger next time. I didn't have enough of an appetite to try a shake or sundae, but I had a good view of the person making the shakes and they were extremely thick.
The place is called Burger Square, I assume because it's located in Franklin Square, since the burgers themselves are the standard round.