To understand what is happening, you first need to understand the issue at hand. Right now, to pass a cloture measure, that is to close a bill to debate and then vote on it, you need 60 votes. In the past Senators wishing to block bills had to by debating endlessly. To address this, a rule was put into place in 1975 which allowed a 3/5 majority of senators sworn in to end debate. It rarely caused issues, until recently when the GOP began invoking the rule of cloture on every single piece of legislation, but then did not stand up to debate. In other words, they abused the rule intended to stop endless debate without actually debating. They would force a cloture vote, but there would be no debate for which to invoke cloture at all.
The new rule would change this simple bit. When the rule of cloture is invoked, a vote is taken on the measure and should it not pass a simple majority, the bill is killed. If, however, a Senator invokes the rule of cloture, and when the vote is taken it does not pass on the 3/5’s majority, but does on simple majority, the floor is immediately opened up for debate. Four calls for debate will go out, and if nobody steps up to debate, the cloture would be voted on again, this time only needing a simple majority to pass. This now ties cloture to the very system it was developed originally for, it ties it to endless debate. Now once the speaker ends, the next call goes out, again up to four times. Each time someone speaks, it resets the calls for debate.
Some are calling this the Mr. Smith rule, after the classic movie Mr. Smith Goes to Washington starring James Stewart. This simple rule change, the tying of cloture to the debate, is one long needed in Washington. As a result, now if a minority party wishes to block a measure, they will have to go on the record as being against it, with footage of it. Now they just can go “no cloture” and can avoid the political fallout of things like blocking the jobs act or stimulus bill.
To remind people what a filibuster properly is, below is an example of a true filibuster, at 8 hours, 34 minutes, Senator Bernie Sanders took to the floor on December 10th, 2010, to filibuster the tax-cut extension deal. This is what a filibuster will mean now, not the farce it has become: