Motive?
They should have moved quickly if the motive was to save lives and increase human well being, and that's the only justification for any sort of intervention in the affairs of another. Who wins or loses with a prospective outcome following the current mess?

I'm afraid that from my no doubt naive perspective, this makes no sense whatsoever. If other Middle Eastern revolutions are a precedent, there will be a bloodbath whichever side wins. Trying to tilt the balance more in favour of the rebels will surely just prolong the conflict and add to the suffering.

If there are justifiable grounds for wanting the rebels to win, then say what they are and give them enough support to ensure a quick victory. Blowing things up from the safety of an airplane in the hope Gaddafi will decide to throw in the towel seems like a compromise that will complicate matters without achieving anything useful.

Of course, if Gaddafi capitulates in the near future the move will no doubt be hailed as a master-stroke, but given the information that is publicly available it will be due to rank good luck and not sensible risk analysis.

does the US want regime change in Libya?

This “liberal intervention” is meant to protect the lives of those who turned against Gaddafi. The UNSC has not authorised regime change.

I can't even begin to predict how this will turn out. I'm usually such an opinionated bugger. But this time the situation is just too muddy for even a wild guess.

Is this intervention going to be seen through the prism of Sierra Leone and Kosovo, or Iraq and Afghanistan, where regime change was swift but where civil war then ensued?

An editorial in The Guardian observes:

This intervention could merely be paving the way for partition, the worst of both worlds: the tyrant and his sons would still exist and the revolution, half finished, could halt on tribal lines.

It says that The resolution rules out a foreign occupation and western leaders repeatedly vowed that the objective was to let Libyans choose their own leaders in freely held elections.

But where and when, in the whole sorry history of western intervention in the Middle East, has this happened? Were Jeffersonian shells fired from US tanks invading Iraq, planting the seeds of democracy in the craters they left? Or does the Iraqi prime minister, Nouri al-Maliki, now behave increasingly like another regional strongman ruling over a country bearing the permanent sectarian scars of a civil war?

As British Tornados, French Dassaults and Canadian F-18s prepare to patrol the skies over Tripoli, it will be business as usual – an intervention which looks much like all the others.

Rebels that run around shooting guns in the air dont usually provide stable governments and life for the people. Its a good idea to separate whether they are right from whether they will be able to provide stability.
This point could be equally applied to Gadaffi.
If Gadaffi is overthrown there will be need for long term help. I would be inclined to look the other way for a little longer.

The elephant in the room is the $32billion (plus) of Libyan assets seized by the Europeans and US earlier this month.

Will this boodle be made available unconditionally to the rebels? If not, what conditions will be imposed? Or will the Europeans and US just keep it?

How independent is a new regime in Libya while foreign Powers control its purse-strings?

Lots of questions. No answers.

It gets a bit hard to defend "liberal interventionism" when it becomes selective, opportunistic and self-interested on the part of the intervening Powers.

Where are the liberal interventions in Palestine? In Bahrain? In Yemen? in Burma? In Africa?

the purpose of the Saudis and UAE troops that had arrived to guard essential infrastructure and restore order on the streets in Bahrain was to put down, by whatever means necessary, a growing rebellion by the kingdom's majority, but deprived, Shia citizens.They are defending the ruling Sunni minority.

The Saudi's are convinced that Bahrain's uprising is being organised by Tehran and that the protesters are fifth columnists for a regime of ayatollahs. The Saudis will not accept a Shi'ite government in Bahrain.

So democracy is not allowable in Bahrain. Stability is required. The Saudi argument is that Iran might benefit if Bahrain embraced democracy and that, as a result, the entire region might become destabilized in ways inimical to U.S. power-projection policies.

Though Bahrain is a small island in the Persian Gulf, it is also the home of the U.S. Navy’s Fifth Fleet, which the Pentagon counts as a crucial asset in the region. It is widely considered a stand-in for neighboring Saudi Arabia, America’s gas station in the Gulf, and for Washington, a nation much too important ever to fail.

The US is once again in familiar territory -- supporting an anti-democratic ruler against his people.

Could America's war in Libya remain limited? Can the U.S. could limit its participation in the Libyan civil war to airstrikes, leaving the fighting to Libyan rebels?

it doesn't look likely that the onset of airstrikes will quickly demoralize Gaddafi's loyalist forces, tips the balance of resolve back toward the rebels, and maybe even convinces Qaddafi to leave town.

A more likely scenario is that Qaddafi may be unable to retake the whole country now, but the rebels may not be able to force him out either in the absence of direct outside involvement (possibly including troops on the ground).