Yes.
If you get a 4g modem on a 4g network, it can be just as fast as cable. I have got 23 down on a 4g air card.
3g can easily play poker and play online games too. It will depends which network, sprint sucks and verizon is good. It will also depend on the signal you get to the device.
But with a solid signal yes, I have even played black ops on a good solid 3g connection with no problems.