Ben Smith has a piece in on Bill Kristol's new Center for American Freedom, an advocacy group with its own conservative news outlet that is modeled explicitly on the liberal Center for American Progress. CAF will host a lot of impressive talent, including Matt Continetti, Bill Gertz, Adam Kredo, and Sonny Bunch, among others.
CAP itself was initially modeled after Heritage, although it has gone beyond Heritage in its advocacy and media operations, and in creating a separate on the increasing politicization of think tanks. As the article notes, over the last few decades, the losing party in many election cycles has created new think tanks in response to its defeat, typically modeled on the most recent think tank versions of the winning party. The phenomenon can be summarized as "lose an election, gain a think tank."
Even within these successive imitations, though, CAP took things to a new level. CAP has an army of full-time bloggers; has promoted the Occupy protests; and its former vice president for communications, Jennifer Palmieri, said in a Bloomberg article about the organization, "Others strive to be objective, we don't." These are not typical activities or attitudes of think tanks, which originally sought to be "universities without students."
The fact that Kristol's organization skips the think tank piece and goes straight to the advocacy, or 501(c)(4), designation, is quite telling: he has apparently determined that you can't get more political than CAP and still be considered a think tank.