I have Verizon Quantum (I think that is what it is called). Wife watches netflix, we both use our laptops, the kid is hosting games on his X-box, and three smart phones are spitting data at as constantly. Never had an issue...triple play price stays the same for phone/internet/tv. Never heard of limits for usage.
The only thing plugged in is his X-BOX (he says it works better that way ????) everything flies around the house on some magical wave. Even the TV (which also has a cable) talks to the router by WIFI for netflix, etc...
All those waves gonna kill us some day.
Now my phone has limits...I think 3gs shared for me and the wife. We try to use WIFI connections as much as possible.