Which gps is the one on the Sprint comercial. I have the 8330 titanium. Maybe it was only for the curve with Nextel. But it seems that you and another can see each others location with the app.
I think the app you saw in the Spint commercial was Loopt. It allows you to see where your friends are - similar to Lattitude in Google Maps. Loopt works with multiple phones and carriers, although some carriers charge for it.