Edit: A commentator complained that this process that follows isn't the only way to "move the window". Well, no, it isn't. But it is one of the things you really, really need in order to make an extreme mainstream: a new extreme for it to be compared against. As the PoMo types are often seen pointing out, you don't have an "us" without a "them".
So, yeah, more stuff about how you turn extreme into mainstream. Here's the first part on defining the Overton Window. Here's the second about the Window, its "stretchiness", and how it impacts the modern debate over legal teen pornography.
Ok, observation the third. If you want the Overton Window movement/stretching technique to work, you need not just two, but three groups. You need the "centrists" of course, to pull things together. You need the extreme guys that you want to make mainstream. But, the thing is, you also need some guy even more extreme than those guy are. Why? Because you need someone for the "new moderates" to point at and say "hey, we're not extreme, look at those guys!" They work in concert with the "middle ground" types, because they provide a new benchmark to set it again, with the new moderates closer to the middle.
Case in point: school vouchers. Not the most successful program, but an apt example. The mainstream had been "publicly funded schools, but they should be well run, with maybe some private schools for rich people and the very, very religious, but they don't get no tax monies". The prospective "new moderate" is, of course, school vouchers, where they have kinda-sorta privatization, but still government money for each individual kid. The religious schools like this a lot because now they can indirectly get state funding for saying that evolution is bunkum, and the elite private schools aren't worried because vouchers ain't going to get any hoi palloi (or, God forbid, developmentally challenged kids) in there to screw up their cooked stats.
Problem, though: vouchers are seen as pretty extreme. It's creeping privatization. How do you make them seem moderate?
Solution: two sets of "hardcore extreme" types, both with a radical hatred of public schooling. The first is the religious types who claim that public schools are indoctrinating their children in Godlessness of whatever sort. The second are the hard "libertarians" who want everything to be privatized because the Market Solves All Ills, and who think the government should get out of education, full stop. Both groups coexist relatively well on this issue.
So you start having these guys nibble away at the edges: talk radio, the Internet, maybe local newspapers. For the Libertarian types, you can also try to sell it to the Powers That Be, because wealthy guys are often all in favour of paying less taxes and not giving a crap about poor people's education.
(Not always, thankfully, but often.)
Of course, most people aren't going to agree with them. They certainly aren't going to change their minds. They are, maybe, nice enough to want to find a way to accommodate them though. Up pops vouchers, and hey! There's a solution. It's a weak solution, but it is one that supposedly "everybody can be happy with", and the guys arguing in favor of it seem so nice, well spoken, and well dressed. Certainly they're everywhere on the TV- because they've been trained and coached on how to best exploit that medium.
Eventually, they win. Vouchers become mainstream, and those saying "um, maybe we should have a secular public education because those are good things" end up being seen as "out of the mainstream", instead of sensible. The "extreme guys" are happy because they're defining the edge now, and may end up "new moderate" later, and to an extent got what they wanted.
Of course, it didn't happen that way. Partially it's because the Dems aren't nearly the pushovers on education that they are on foreign policy, and also because vouchers are terrible policy. They're out there, sure, but they're hardly ubiquitous, and the debate over them has died down. Education itself isn't the issue it was with Iraq looming over everything, but even so, vouchers didn't succeed to the extent that people wanted.
You take that education example and apply it to foreign policy, though, and the whole thing still makes perfect sense. It was a lot more successful, too.
The lesson for progressives? Well, oddly enough, it's that those far-left guys are actually necessary for you to succeed. You need to be seen as the "reasonable compromise", while still being on the edge of the Overton window prior to movement. They're the way you're going to do that. Maybe not the hardest of the hardcore socialists, but the protest-happy guys with all the black bean burritos and suchlike? Yeah, they're the ones. Trying to seperate yourselves from them doesn't work, because right now they're not doing anything to pull the window in their direction. You have to help them a little, on the "DL", to have more of a voice, because then you look like the compromisers and solution-builders.
And, in turn, you need to ensure that the far-extreme righties are not just seen as outsiders, but actively ignored as a part of the debate. (Kind of like how the lefties are now.) How to do that? The right points the way: either completely ignore them, treating them with a kind of benign indifference, or some kind of active mockery. That's why I like sites like the poorman so much- because humor is the single best way of invalidating a nonsense argument. Don't get mad, or get even. That pulls them into the debate.
Just make them look silly, and refocus things on the debate that you want to have.