Political scientists called upon (or who volunteer!) to comment on what's happening in contemporary politics must, if we're honest, do a whole lot of deflating. No, this event isn't really unprecedented. No, that speech isn't really going to change the political landscape. No, elections probably do not ride on the vote on some bill.
And there's plenty of that's been appropriate over the course of the health care reform debate over the last year, and there will be more of it today and going forward (as Seth Masket says, we're in for plenty of unjustified hype about the electoral effects of health care reform). But still, and trite as it may be to say it:
This really is a major, major, event. It's fully deserving of all the hype. It is not, of course, a "government takeover of one sixth of the economy" in any literal sense at all. But while that rhetoric is wrong in any literal sense, what is happening here is a choice to adopt what Ted Kennedy used to say for so many years: that health care is a right, not a privilege. If the bill passes today, and if it is implemented over the next few years, the United States really is going to join the nations of the world that collectively arrange for every citizen to receive health care, just as the United States, beginning in the 1930s, decided that a decent retirement would be a right. It's not a government takeover, but it does amount to taking on the responsibility of organizing health care so that no one goes without.
Of course, that leaves plenty of arguing about the details, and of course the bill(s) today don't actually achieve universal coverage. Liberals who support the bill have argued to liberals (and further left) who oppose it that this is how things work in America; this is how it worked with Social Security, Medicare, and for that matter with Civil Rights. In this, I think the proponents of the bill are absolutely right. Our political system doesn't allow fully-formed, specialist-produced solutions to major problems. This is what big change, especially big change in the liberal direction, looks like. It doesn't happen often, but for once the hype is absolutely correct: this will be, if Nancy Pelosi has the votes, a very important piece of legislation, in some ways the most important bill to pass in forty years.