Hi
Sennheiser has some highly regarded wireless cans using Bluetooth technology, e.g. the PX 210 BT.
Don't get a skrik when I say Bluetooth - these use a special, designed-for-hifi Bluetooth profile called apt-X.
(apt-X was developed for pro use and sounds a lot better than the A2DP (average) or SBC (ghastly) profiles.)
apt-X is also used by Chord in the latest revision of their Gem DAC, and Creative has released some good implementations of the technology like the D5 wireless iPod speaker dock.
The downside is you'll also need to buy a separate Bluetooth dongle/transmitter like the BTD300.
Still, a much better solution, technically speaking, than any kind of FM-based wireless tech.
Nidri