It seems like every time I'm in a store that sells speakers I hear someone asking about wireless speakers.
It's a great idea, but then reality sets in: wireless speakers always have wires.
And get this: most wireless speakers have more wires than standard "wired" speakers. Think about it--a regular speaker has a wire that delivers both power and signal to the speaker. Since wireless speakers aren't "powered" by your receiver or amplifier, they have to be plugged into an AC power outlet (that, or come with built-in power amps that must be plugged into a power outlet). Another wire connects the amp to each speaker.
Affordable wireless speakers are never terribly good speakers. It seems like all of the engineering effort is directed at the wireless part, and sound quality is an afterthought.
Sure, transmitting signals to the speaker is relatively easy, but wireless receiver electronics are likely to degrade the sound compared to conventional wire. So wireless costs more and sounds worse! Nice!
A lot of folks want wireless speakers for use in surround channels, so they won't have to run wires from the front of the room to the back, where the surround speakers are. Wireless systems are good for that, but they still have to plug the "wireless" amplifier into a power outlet, and run wires to the "wireless" surround speakers.
So either accept that wireless speaker systems come with their own set of problems, or wire the speakers. That's a lot cheaper and a better-sounding solution.
OK, I know of one truly wireless system, the Griffin Evolve iPod dock speaker system. The battery-powered speakers can't play all that loud, have weak bass, limited dynamic range, and generally low fidelity. But they are really wireless. And no, I don't think they could be used in a home theater system.