The new war in Libya is so new and fluid that it is hard to determine what is really going on or will go on, but I think a highly likely outcome will be a de facto partition of Libya. While the mandates from the Arab League and the UN Security Council only supported a no-fly zone to prevent Qaddafi's forces from killing civilians from the air, and this is the official position of the US, many leaders in the US and more openly in France and Britain, which are very prominent in the military action, have stated that the goal is to support the rebels and remove Qaddafi, with both Obama and Clinton effectively supporting this with statements that Qaddafi has lost legitimacy and should step down. Some observations I have not seen made elsewhere follow.
That a partition that could become semi-permanent may be the result arises from the obvious possibility of a military stalemate. Without the move to no-fly zone, it is likely that Qaddafi's forces would have fully defeated the rebels, having reached the outskirts of Benghazi, the rebel capital, after having retaken most of the major oil towns to the southwest of Benghazi, although one major city in the west, Misurata, continues to be held by the rebels. Even with his air force subdued, Qaddafi retains the superior edge in ground military force. It is unlikely the rebels can defeat him without outside ground support, and it is increasingly looking like there will be no active support from any Arab country in the air, and much less likely on the ground. Obama has stated the US will not deploy (and there will be major resistance to doing so from the US military), leaving only maybe the Brits and French to do so, but my guess is they will be reluctant to do so in sufficient force to overthrow Qaddafi without the US or Arabs involved, and parts of the rest of the world becomning more critical (both Russia and China have expressed "regret" over this new military action, despite their abstention in the UNSC vote because of the Arab League resolution). So, a likely outcome is a military stalemate after some further shuffling of the positions on the ground.
If Misurata falls to to Qaddafi's forces while the rebels control much of the east, what will emerge will look like the longstanding historical division between Tripolitania in the west and Cyrenaica in the east, the names of Roman provinces in those areas (a third province in the southwest, Fezzan, is essentially part of the western zone). Throughout most of history they have not been jointly ruled, and when they have, they have been distinct provinces. There are deep differences, with the population in the west having a substantial Berber element (Qaddafi and his tribe are actually "Arabized Berbers," that is, ethnic Berbers who speak Arabic). The east has often been ruled by whomever was ruling Egypt (and Egypt is the only Arab nation that might or could enter the action on the ground, and the current Arab League president, Amr Moussa, who is the main person responsible for their resolution, is running for President of Egypt and strongly supports the rebels). There have even been religious differences, with the east basically Maliki Sunnis, whereas there continues to be a Khariji Muslim community in the west, mostly concentrated in the Berber areas. More broadly, Tripolitania in the west has had long periods of independence, either de facto or de jure, including during the "Barbary pirates" period when the US warred with Tripolitania in the early 1800s, a period when Cyrenaica was under Ottoman rule (the Ottomans got back into Tripolitania later in the 1800s).
There is a further warning here having to do with history, specifically the fact that among the leading countries involved in this military action are the three European countries that ruled parts of modern Libya prior to its independence as a kingdom in 1951, namely Italy, France, and the UK. Italy began taking over Libya from the Ottomans in a war in 1911-12, although it was not able to subdue Tripolitania until 1923, with Libya as a unified entity under Italian rule declared in 1934. During WW II, the French came in from Algeria and took Fezzan in the southwest in 1943, while the British took control of the coastal provinces in warfare with Germany during 1941-42. Italy formally surrendered control in 1947, and the UN established a mandate under the joint control of France and Britain. In 1949, the British established a kingdom in Cyrenaica (capital, Benghazi) under Idris al-Senussi. When Libya was granted full independence in 1951, Idris was made king of all of Libya, but with the capital in Tripoli, triggering much resentment in the west of this rule by easterners, an important point in the current situation. In 1963 the old provinces were officially dissolved in favor of smaller administrative units. Qaddafi seized control in 1969, and while he is a despicable leader and human being whom I would love to see overthrown, when he falls back on old pan-Arab anti-colonialist rhetoric, he is not entirely talking through his hat in the eyes of many obervers around the world who know their history.