Comcast is making further inroads into the U.S. wireless market with the launch of its High-Speed 2go service in Boston, which will run on Sprint’s 3G network. Comcast says it will launch a 4G version of the service on Clearwire’s WiMAX network “later in the year.”

Comcast is bundling its latest mobile broadband offering with its Internet, television and voice products. Current customers will be able to subscribe to the 3G service for $40 per month.

Comcast currently resells Clearwire’s WiMAX service in several markets throughout the country, including Portland, Ore.; Las Vegas; and Chicago. Together with Intel, Time Warner Cable, Google and Bright House Networks, Comcast invested $3.2 billion in Clearwire in late 2008.