Finally! We thought that fancy new Android device for T-Mobile would be pretty slow if it didn’t have much of a 3G network to run on. T-Mobile, which currently has 3G service in 13 major markets, is launching in Atlanta, Chicago, Los Angeles, Orlando, Philadelphia, Sacramento, San Francisco and Seattle just in time for the HTC G1 launch next week. By the end of the year, T-Mobile plans to roll out 3G services to six more markets – Birmingham, Denver, Detroit, Kansas City, Memphis and Tampa – bringing its total 3G coverage to 27 markets or about two-thirds of its customer base.