To do this, expect to have to work 100% around any acceptable system you can find.
1) You will WANT to get a gaming solution. Why? All others wont care about latency.
2) Bluetooth is good There is the other better one... (whats the name of it)...
3) hack a wireless joystick
4) hack a wireless mouse.
and be as happy as you can with the end results.
but don't think you will find a good generic usb wireless connection.. you will be converting the values left and right... then slowing them down inbetween.
btw, I've heard there is one good bluetooth mouse. I can't remember if it was the microsoft one or the logitec one.
As for the joystick. You might find some pc bluetooth items. You might get better results with a console controller and convert it since they have been doing it for a lot longer
I would love to hear what you come up with

I would LOVE to see this working on a little handheld type small system. I want to take one of those small via motherboards and put a screen on it... and the only connection to it is a wireless thumb pad (for traveling... and you can hand the screen on the seat infront of you)...