Datel's 3rd-party Xbox 360 Bluetooth headset has popped up on Amazon UK with a shipping date of the 30th of June and with a price tag of £59.99/$109. Originally the headset was said to ship on the 17th of March, but there's still no mention of it on the company's website, so it's possible that Amazon jumped the gun by placing it on their site. If it does ship when they say, it'll have the market for wireless Xbox 360 headsets to itself for quite a while; Microsoft hasn't said anything more about when their official headset will be released.
The device itself is a bundle of what appears to be a relatively generic Bluetooth headset--it looks strikingly similar to Motorola's HS820 headset--coupled with a dongle that attaches to the controller's standard headset port, packaged together in a standard Xbox-green and white box.
[Via Xbox 360 Fanboy]