We were just discussing this on the "Help Me Choose a Soundbar" thread.
There are a few but all come with compromises.
The "wireless" conceit is a bit misleading since powered speakers still need to be plugged in. So you may save the wire to the back of the room but your placement and "cleanness" of installation will be driven by location of power outlets and power cable routing options.
I have not heard any of these yet but here is what my search came up with:
JBL Bar 5.1 This one is TRULY wireless as far as I can tell as the surround speakers dock to the main speaker for casual listening and charge while docked. When you are ready for surround you undock them and move them to the surround position. Of course you are now getting whatever power that battery can put out for however long it can last (basically this is now like a couple rechargable bluetooth speakers providing surround sound). And you have the hassle and wear and tear of constantly moving the speakers.
Samsung HW-Q90R - This is a Samsung/Harmon Kardon co-branded 7.1.4 system. The rear speakers (including surround and upward-firing speakers) need power connections. This looks pretty slick but is insanely expensive - you could get a nice AVR-based surround system
installed with all the wires hidden for what this thing costs.
Monoprice SB-600 - This Monoprice 5.1.2 unit claims to be wireless surround but perusing the installation guide it looks like there is actually a cable required between the two rear speakers. Depending on your installation this might be a deal-breaker or an easy compromise.
None of these are for me, but it does seem like we are getting closer.