In Misrata, the airport has fallen to the rebels. They are also pushing westward from Misrata into Ziltan, which has been occupied by Qaddafi troops but is definitely a pro-rebel city. There are probably some very poorly armed underground resisters there, as I've read various things about occasional combat in the city. Also, for the first time today, I saw video of rebels in Misrata using mortars.
The rebels in Misrata are kicking Qaddafi's ass with help from NATO. But they pay for territory in blood; in the combat videos casualties are fairly frequent. I don't think that they have enough manpower to make it all the way to Tripoli. Furthermore, as they push out from Misrata they'll be leaving the urban terrain that has served them so well, and will be extending their perimeter more and more, leaving their defenses thinner and thinner and ripe for a Qaddafi counterattack. If the rebels want a knockout blow, I believe they'll need to link up Misrata and the larger forces in the East. The Berber rebels in the Nafusa Mountains are doing a good job of holding their ground and serving as a distraction to Qaddafi, but I don't think that they have enough weapons to make a meaningful offensive unless they can link up with one of the other rebel enclaves, which is unlikely, because they are quite isolated up there.
For now, NATO needs to keep hammering Brega and any supplies Qaddafi tries to move to there along the coast road from Sirte and Tripoli. Unfortunately I don't think they have enough air resources to carry out terribly effective bombing in all of the theaters in Libya at once. NATO seems to be focusing on Misrata and Tripoli. I think that's a mistake; Misrata will stand on its own now and the bunkers they're hitting in Tripoli are probably empty anyway. They need to break Qaddafi's forces in Brega and clear the coast highway.