Even though a no fly zone would require more than its fan suggest (bombing of anti-aircraft systems, etc), it would still be a half-measure. It would be doing enough to be involved but not enough to make much of a difference. It would make the West feel better, but would it tilt the balance on the ground? No. Given how ineffective the Libyan air campaign seems to be, a no fly zone would fit the "doing just enough to appear to be doing something" bill. I am not sure putting in Special Forces to help the rebels would make sense either, but at least it would have a chance of making a difference.
Just a short rant to counter the theme of the day.