iPod Bluetooth Audio Transmitter
No, it's not from Apple... but this ExtremeTech article reports on currently prototype designs of Bluetooth (wireless) audio transmitters from a company called Infinite Range.
According to the article, a number of companies will be producing devices based on this design in the coming months. In particular, iPod add-on vendor XtremeMac admits that they plan on releasing an "iPod enhancement" based on this design.
The design is a simply a transmitter/receiver pair that transmits audio over Bluetooth. Of note to audiophiles, the devices does on-the-fly compression to transmit the audio possibly compounding the already lossy compression of AAC/MP3.
Apple has recently been partnering with companies such as Altec Lansing and Belkin to introduce new accessories to the iPod line. One recent unconfirmed rumor did claim that a bluetooth dock/headphone pair was in the works. While this rumor was largely dismissed, it's possible that this development may have been the basis of it.