I think as My Name is Earl hit the homestretch of its second season, it lifted itself from being a decent quirky hit that compliments shows like 30 Rock, Scrubs, and The Office to being a great show itself (note: I wouldn't count 2 of the three shows above as great shows yet although 30 Rock has shown flashes).
"My Name is Earl" works as a quirky no-laugh track show that used to get by on the star power of Jason Lee and the comic gifts of Jamie Pressley. It's storylines have a little humor and that humor is usually balanced by the feel-good aspects of the show. In other words, it's like "Touched by an Angel," only funnier. As of late, however, I think the show has not only been funnier than Touched by an Angel, but it's become funny period and as for the "Touched by an Angel" factor, I think the show has been moving into deeper territory to the point where we're actually caring about the characters' evolution from one episode to the next. It's starting to become dynamic and characters are starting to grow past the requirements of what would make the laughs meaningful within a half-hour episode. Earl is trying to grow up by getting an education and a job and he's taking his brother with him. Jamie is trying to become a mom and like The Office last season, the season finale ended with such a bang of a cliffhanger, it cemented the show as Must-See next year.