Interpretations regarding what it meant will be myriad, but it's pretty well established that it was historic

I think the list of four things Rand Paul's filibuster accomplished that is offered by Thomas Lifson at The American Thinker distills its significance pretty well.

The point is not, as the dismissive remarks of Graham and McCain suggested, whether a drone strike on an American citizen, without due process, is very likely or even remotely likely.  It's about being very clear, as we must be in all matters of policy and governmental action, on what kind of authority the Constitution bestows on whom.

And, in the climate developing this week, as the sequester does not cause mass societal chaos, Rand's stand has made the Most Equal Comrade squirm.  It brought the invincibility of the Freedom-Hater regime into question.  It showed us an alternative to despair.  The overlords and their Reasonable Gentleman sycophants do not like it one bit that we actually exercise this thing called our liberty.