A filibuster is an attempt to prolong debate, typically used by the minority to prevent passage of a bill with majority support. Best exemplified in the movie Mr. Smith goes to Washington in which an honest Senator battles against graft and corruption by taking to the well of the Senate and stands his ground until the corruption is exposed and his rivals defeated in shame.
It's hard to believe that just 2 years ago, the Republicans attempted to kill the filibuster entirely. They complained that the Democrats were abusing the system by denying a vote on 10 of Bush's 229 judicial nominees. Former majority leader Bill Frist invented the idea of the "nuclear option" to strip the minority of it's right to continue debate.
But times change. Mitch McConnell embraced the idea of the filibuster within days of the 2006 elections, after the Republicans lost both Houses of Congress. Since January, he's blocked votes over 40 times, on everything from funding renewable energy to implementing the 9/11 Commission's recommendations. No more talk of "up or down votes". Today he's all about minority rights .... well in the Senate, anyway.
So it's good to hear that Harry Reid now plans to start making Republicans take to the floor of the Senate if they don't want to cut off debate.
I'm guessing Senator McConnell isn't going to cut as sympathetic a figure as Jimmy Stewart while he's on the Senate floor arguing against ethics reform and increasing the minimum wage.