I think some people are misunderstanding what the OP is talking about. I'm pretty sure he's talking about actual wireless services, like XFinity by Comcast. With those, the ISP runs a line out to various access points, which whole neighborhoods connect to. This is much different than having your own cable connection with a wireless router on the end and a PC 4 feet away.
From what I've heard, those services can be pretty darn decent as long as other people on the network aren't using up all the bandwidth. It also depends on your location and how many hops you have to take...as well as how far you are from the access point.
For what it's worth, even cellular wireless can be pretty decent. I tethered my phone and used that connection to play BF3 on my laptop while I was in a hotel last year. My ping was between 120 and 150, and was enough for me to remain competitive.