Ford announced Tuesday that select vehicles in its 2010 lineup will feature HD Radio, a technology that enables users to “tag” song they listen to for later purchase on iTunes.

HD Radio is a terrestrial radio format supported by almost 2,000 radio stations in the U.S. The technology provides improved sound quality, support for “multicasts” (mini-stations that are spun off of the main station), and embeds digital information in the carrier wave signal. Unlike satellite radio, you don’t need to subscribe to HD Radio, though you do need a radio receiver capable of decoding the information.

HD Radio has been an option on third-party head units from aftermarket car radio manufacturers for several years; it’s also available in some desktop and home audio sound systems.

Ford claims to be the first auto manufacturer to offer HD Radio as an option in factory-installed car stereos. Ford’s news comes on the heels of an early December announcement from HD Radio maker iBiquity indicating plans from several luxury auto manufacturers to offer HD Radio as an option in new models, including BMW, Volvo, Audi, Mercedes-Benz, Jaguar and Rolls Royce.

One of the most prominent features of HD Radio for iPod users is iTunes Tagging. When you hear a song you like, you push a “Tag” button on the radio display. The song information is stored in the radio’s memory. The radio can retain up to 100 tags. When you connect your iPod to the car’s radio, that tag information is downloaded to the iPod. The next time the iPod is synced to your computer, it will create a playlist of tagged songs – you can then preview them and purchase them in the iTunes Store.