This Sunday during a long soccer game drive my iPhone was:
A) The GPS (Navigon)
B) The audio (Slacker)
C) The hotspot (MyWi)
D) The phone (a couple of calls and use of my BT headset)
WiFi was serving up data to my iPad (son's girlfriend was watching Netflix), my son's Touch (surfing, FB'ing, etc.), and one of his friends Touch (Netflix, surfing, etc.)
It handled all of this just fine. No interruption in music and the kids told me there were a few Netflix hiccups during the 1.5 hours of driving. Pretty impressive if you ask me!