The silly Americans have now decided that not just a no-fly zone is required but rather that full scale bombing of Libyan army units is required:
http://www.bbc.co.uk/news/world-africa-12768695
This sort of stuff is dangerous because if it happens it opens the floodgates for other countries invading or bombing their neighbours on dodgy humanitarian grounds.
To be honest, the West doesn't know what's happening in Libyan parts controlled by Gaddafhi.
The action that's been portrayed on the news seems legitimate from a military perspective (artillery duels, bombing of rebel positions - all legitimate under current rules of war).
Bombing the guts out of Libya legitimises other countries doing too - e.g. Israeli strikes in Lebanon or Russian engagement in the Caucasus.
It even legitimises Serbian military involvement in the Balkans in the 1990's - after all the Serb military's excuse for being in Croatia and Bosnia was to protect Serbs who were being persecuted by majority Croats and Muslims.
Even if it has UN sanction, it creates further precedents that undermine global stability. One day the US will not be the top dog and the new powers with even poorer human rights or peace records will use the precedents sent now to further push their own agenda.