This is the best way I can summarize how good I feel about Glee's renewal for a second season:
That said, I have a couple of concerns about the show, and a couple of proposals. First, the show's main characters appear to be at least juniors in high school. That means they're time-limited, or the show's going to get awfully awkward. I think the best way for Glee to stay fresh and viable, if the show and the network are hoping for an extended run, would be to make clear that some of the characters are in different graduating classes. That way, the show could move characters in and out in a way that feels logical, while giving viewers some continuity from season to season. There are so many characters in the show who haven't had major storylines yet, that it should be possible to do this within the existing cast.
Second, the show's going to have to find a way to keep the competition around which it's structured fresh each year. I was actually thinking this morning about the debt the first half of Glee's freshman year owes to Bring It On (shut up, the original is genius). You've got the eager new leader with questionable leadership skills (Lea Michele or Kirsten Dunst) taking charge of a fractious squad. At a critical moment in both the movie and the show, both the New Directions' and Toro's routines are leaked to the competitors. Cheerleading coach Sue Sylvester is a better-written and expanded version of the evil choreographer Sparky Polastri role in Bring It On--both of them sell out the team at the center of the show or movie, Sue for pleasure, Sparky for profit. And I think Bring It On may offer a wise way for Glee to end its first season: New Directions should lose. If the glee club wins it all in their first outing, all the dramatic tension will dissipate. Losing gives them something to rally around, and to fight over. It provides a motivator for the second season. And maybe even for Mercedes to coup Rachel!