Here's the explanation from Take Back Medicine:
Senate schedule & next steps
The Senate will begin formal debate on the healthcare bill after the Thanksgiving recess. At that time amendments may be introduced as well, which will likely number into the hundreds. Debate will probably take up to 3-4 weeks, so that brings us up to Christmas recess. Even if it passes the Senate then, it would have to be reconciled with the House bill, which is significantly different.
First, let's be clear - the vote tonight was only to proceed with formal debate. The bill can be filibustered, and some have indicated that they will do so. That means that the Senate would again have to invoke cloture to end that debate. The votes required for that are 60.
Those votes would come before we even get to a final vote on the bill. So when you hear that the Senate voted to pass the health care bill - THAT IS NOT CORRECT!
On the same page, they posted an interesting piece on cloture. Scroll down (at TBM site) to read the whole article, but here is the brief history which is quoted:
March 8, 1917 Cloture Rule
Woodrow Wilson considered himself an expert on Congress—the subject of his 1884 doctoral dissertation. When he became president in 1913, he announced his plans to be a legislator-in-chief and requested that the President’s Room in the Capitol be made ready for his weekly consultations with committee chairmen. For a few months, Wilson kept to that plan. Soon, however, traditional legislative-executive branch antagonisms began to tarnish his optimism. After passing major tariff, trade, and banking legislation in the first two years of his administration, Congress slowed its pace.
By 1915, the Senate had become a breeding ground for filibusters. In the final weeks of the Congress that ended on March 4, one administration measure related to the war in Europe tied the Senate up for 33 days and blocked passage of three major appropriations bills. Two years later, as pressure increased for American entry into that war, a 23-day, end-of-session filibuster against the president’s proposal to arm merchant ships also failed, taking with it much other essential legislation. For the previous 40 years, efforts in the Senate to pass a debate-limiting rule had come to nothing. Now, in the wartime crisis environment, President Wilson lost his patience.
Decades earlier, he had written in his doctoral dissertation, “It is the proper duty of a representative body to look diligently into every affair of government and to talk much about what it sees.” On March 4, 1917, as the 64th Congress expired without completing its work, Wilson held a decidedly different view. Calling the situation unparalleled, he stormed that the “Senate of the United States is the only legislative body in the world which cannot act when its majority is ready for action. A little group of willful men, representing no opinion but their own, have rendered the great government of the United States helpless and contemptible.” The Senate, he demanded, must adopt a cloture rule.
On March 8, 1917, in a specially called session of the 65th Congress, the Senate agreed to a rule that essentially preserved its tradition of unlimited debate. The rule required a two-thirds majority to end debate and permitted each member to speak for an additional hour after that before voting on final passage. Over the next 46 years, the Senate managed to invoke cloture on only five occasions.
U.S. Congress. Senate. The Senate, 1789-1989, Vol. 2, by Robert C. Byrd. 100th Cong., 1st sess., 1991. S. Doc.100-20.
Also worth reading is an article by Jane Orient, "Forget the Trees; Look at the Forest on Healthcare." Nothing earth-shakingly new, but just a clear and succinct explanation about the Republicans and Democrats quibbling over how they are going to take over medicine, while the real issue is that they shouldn't be involved at all!