Mac4Ever.com (French) publishes information from Bogdan Nedelcou, car product manager of Motorola, in a recent radio interview.
The interview with Nedelcou reveals that consumers will soon be able to listen to music wirelessly from their iPod through their car speakers. The upcoming wireless-capable iPod is expected to include Bluetooth technology.
Apple has also incorporated Bluetooth technology into its iBooks and PowerBooks.
Update: One user points us to this patent from Apple which was filed in April 2003 which describes a "wireless media player system that includes a hand held media player capable of transmitting information over a wireless connection and one or more media devices capable of receiving information over the wireless connection".
Update 2: Image from patent depicting the wireless iPod.