We're almost 10 years into the MP3 revolution, and much of the controversy has finally dissipated. The digital music lawsuits have mostly been settled. High-profile music-sharing services have come, gone, dived underground, or, as in Napster's case, have come back again on a subscription model that pays its dues to the recording industry. Meanwhile, Apple has helped to legitimize the digital distribution of music, as people now happily download songs at 99 cents each from Apple's iTunes Music Store and save them onto the 20GB hard drive in their iPod portable music player.

The first portable MP3 players were flash-based, but the category really took off when tiny 1.8-inch hard drives offered enough storage for a 10,000-song library that you could carry in your pocket. In Q4 of last year, Apple shipped 2 million iPods and reported 4 million song downloads a week on its iTunes Music Store. Recent consumer research has reported that as much as one fifth of all young people are planning to buy an MP3 player by the middle of this year. So, the MP3 revolution is alive and well, and it's motivating mobile electronics manufacturers to join its cause.

Which begs the question: How do you hook up an iPod to a head unit so you can blast your music collection from the sound system in your vehicle? An automaker, not the aftermarket, has taken the first step to popularize, in a big way, the idea of MP3 player integration. BMW's iPod adapter can be installed in '02-or-later 3 Series, X3 and X5 SAVs, and Z4 Roadsters, combining the ultimate driving machine with Apple's MP3 supercarrier into a relatively seamless package. Users park the iPod in the glovebox, connect it to a cable that runs to the factory head unit, and can control the iPod with buttons on the steering wheel.

For the rest of us who are not Beemer jockeys, there are similar aftermarket solutions. The quickest, easiest, and least-satisfactory way to listen to an iPod during the morning commute is with a wireless transmitter. These little gizmos plug into an iPod's headphone jack and then broadcast an FM signal to frequencies at the low end of the radio dial. Units that give you a frequency selection, like Mito Corp's AudioBUG, are the best choice. In any event, there will inevitably be some signal loss when using any of these transmitters, but they're cheap and do away with the need for cables.