Panasonic has introduced its latest style of high-definition televisions in Chicago and Denver, which are the first U.S. areas to get access to the interactive cable service that doesn't need a set-top box.

Panasonic launched the 42-inch and 50-inch Viera Plasma HDTVs in a joint announcement with Comcast, the first cable operator to offer the so-called tru2way service in the United States. Tru2way, a technology developed and licensed by the cable industry's research arm, CableLabs, provides basic features, such as an on-screen guide and video on-demand content, simply by plugging the cable directly into an HDTV.

Comcast and Panasonic have worked together in making sure TVs are available in the areas where the cable operator is debuting the service. "We see tru2way technology as the gateway for our customers to experience the next generation of interactive television, and our work with Panasonic to develop and support the first fully digital-cable-ready HDTVs is an important first step in making that happen," Mark Hess, Comcast's senior VP of video product development, said in a statement released Wednesday.

While Comcast is starting with basic features, tru2way has much more potential. For example, the technology could be used in the future to enable cable TV watchers to vote for contestants on American Idol, buy products on the Home Shopping Network, and get access to play-along apps for game shows. Cable operators could also introduce premium upgrades of the technology to squeeze more money from subscribers.

While tru2way doesn't need a set-top box, users would still need to have special hardware to decrypt premium cable programming, such as HBO or Showtime. Tru2way TVs come with slots to plug in the CableCard, which is also developed by CableLabs.

Panasonic is selling its new TVs in Abt Electronics and Ultimate Electronics stores in the Chicago and Denver areas, respectively, and in Circuit City locations in both cities. The suggested retail prices are $1,600 for the 42-inch set and $2,300 for the 50-inch model.

Comcast plans to introduce tru2way services in other cities during the coming months. The company, however, will not be the only major cable operator to offer the service. The industry has committed to deploy the service by the end of the year in areas covering more than 90 million U.S. homes.