Even though good rap groups today are pretty much non-existent, if you are looking for one from this millenium, I would point you in the direction of Little Brother. They hail from North Carolina and are made up of three members, Phonte, Rapper Big Pooh, and 9th Wonder (producer). Their debut, The Listening, has a spot somewhere in my top 10 hip-hop albums of the 2000's. Best songs off the album, imo, are For You, Whatever You Say, and The Getup. If you are looking for a break from the T-Pain/Ne-Yo/whatever else is on the radio BS, I suggest you give this album a listen. Another cool thing about the album, it plays through like a radio station (similar to Snoop Dogg's debut Doggystyle, although the comparisons between the two stop there), so it makes for an entertaining listen.
One more tidbit about Little Brother. After the release of their second album The Minstrel Show in 2005, BET refused to play the single (Lovin' It) on their station, claiming Little Brother was too "conscious." It's pretty sad that BET uses that as a reason not to play their videos, considering the messages some of the other artists they play send with their music.