Yeah, a no-fly zone would help (especially in giving the rebels a secure rear area), but it's the armor and heavy artillery that's really the problem. Even though you did have some tanks captured by guys wielding hunting knives, those are going to be the exceptions to the rule.
AJ now reporting that rebels have retaken Bin Jawad (village west of Ra's Lanuf, about 1/2 of the way to Sirte), so it looks like they're continuing the push west after the initial setbacks this morning.
Also reports that tanks made it into the main square in Misrata, but are now trapped and under siege by the rebel forces there.
UPDATE: At least one tank destroyed in Misrata, possibly more. Indications now are the rebels basically pulled a Cannae tactic and allowed the lead armor platoon to make it into the city center, then encircled them and let 'em have it.
Also, reports are emerging from Az-Zawiyah stating that the rebels have beaten back government forces, capturing 4 Land Rovers with anti-aircraft weapons, tanks and jeeps and killing 21 government troops. If true, that city is full of badasses.
And...the US is starting to pull people out of Yemen, after four government soldiers there were ambushed and killed amid growing protests. Not clear if the ambush was linked to the protests or was an al-Qaeda attack (AQ is very active in Yemen, and any popular uprising there has to be scrutinized a lot closer for links to AQ)
2nd UPDATE: Rebel forces in Benghazi captured an 8-man team of British SAS paratroopers. Apparently, the SAS team were bodyguards for a junior diplomat who the British sent to enter into negotiations with the National Libyan Council in Benghazi. But either the Brits didn't tell anyone they were coming, or the message just didn't get out to the right people (understandable, given the chaos on the ground and the ad hoc nature of the provisional government). Looks like no harm, no foul -- the SAS team and diplomat are safe and accounted for, and the NLC said it's just waiting for the British government to vouch for them. Wonder if this portends official recognition by the UK of the NLC as legitimate government of Libya? That could trigger a wave of similar formal recognitions.