My brothers and I are season ticket holders for Seton Hall Men's Basketball, one of the three teams to play at the Prudential Center ("The Rock") in Newark, NJ (both the Nets and the Devils play there as well). I was amazed to find this season that they have an entire cart dedicated to Gluten Free eating!
The cart sells a variety of drinks, hot dogs, sausages, and snacks. The hot dogs and sausages are cooked on a rolling grill (like you'd see in a convenience store for example). The hot dogs are Nathans (who within the last year or two removed the gluten they were adding to their hot dogs) and the sausages are Premio. They also have Glutino GF Pretzels.
While the hot dog buns are gluten free (they're made by Ener-G), the sausage rolls are The Grainless Baker and contain dairy. There are mustard packets available at the cart and I recommended to them that they offer relish packets as well. (Both relish and sauerkraut are available from the regular condiments stations but they are open and quite susceptible to cross contamination.)
Oh, and the best part? The Gluten Free Hot Dogs are the exact same price as their gluten containing brethren at the regular concessions. (Yes, still over priced, but it's nice to not have to pay even more!)
Updated - 4/25/11
Now that Udi's is making a hot dog bun, I wonder if they'll switch?