I work in the wireless industry. There's MANY ways to create wireless speakers. Sadly, there's still no way to do it and have it sound great. The RF interference and latency issues wreak havoc on the sound quality and timing, so up to now there's never been any successful products.
Companies have tried Wifi and Bluetooth but those are plagued by interference from normal network equipment. Other frequencies are crowded with other consumer products.
Apple has potential solution using Airtunes and Airport Expresses, I've found the latencies to be almost nil if you can reach all Expresses w/ one access point. But those require powered speakers and there's no multichannel implementation.
Honestly, the best wireless speaker I've heard isn't even stereo. A friend has a 900 MHz Brookstone speaker that actually sounded REALLY good, kind of like how a Tivoli sounds great with one speaker. Must be doing well, they've been selling it for years.
http://www.brookstone.com/indoor-outdoor...ist1FDT|7141633
