Joe Scarborough implores Republicans to denounce Sarah Palin:

Republicans have a problem. The most-talked-about figure in the GOP is a reality show star who cannot be elected. And yet the same leaders who fret that Sarah Palin could devastate their party in 2012 are too scared to say in public what they all complain about in private.
Enough. It’s time for the GOP to man up.

In fact, many Republicans are castigating Palin in public. There's Karl Rove:

“With all due candour, appearing on your own reality show on the Discovery Channel, I am not certain how that fits in the American calculus of 'that helps me see you in the Oval Office’,” Mr Rove told The Daily Telegraph in an interview. […] “There are high standards that the American people have for it [the presidency] and they require a certain level of gravitas, and they want to look at the candidate and say 'that candidate is doing things that gives me confidence that they are up to the most demanding job in the world’.”

Peggy Noonan:

Conservatives talked a lot about Ronald Reagan this year, but they have to take him more to heart, because his example here is a guide. All this seemed lost last week on Sarah Palin, who called him, on Fox, "an actor." She was defending her form of policical celebrity—reality show, "Dancing With the Stars," etc. This is how she did it: "Wasn't Ronald Reagan an actor? Wasn't he in 'Bedtime for Bonzo,' Bozo, something? Ronald Reagan was an actor."
Excuse me, but this was ignorant even for Mrs. Palin. Reagan people quietly flipped their lids, but I'll voice their consternation to make a larger point. [… Reagan] wasn't in search of a life when he ran for office, and he wasn't in search of fame; he'd already lived a life, he was already well known, he'd accomplished things in the world.

Spencer Bachus:

Rep. Spencer Bachus, R-Ala., a favorite to become chairman of the Financial Services Committee in the incoming Republican-controlled House, said that while tea party candidates fared well in House races, in the Senate "they didn't do well at all," according to the Shelby County Reporter.
“The Senate would be Republican today except for states [in which Palin endorsed candidates] like Christine O’Donnell in Delaware,” Bachus said at the November 4 meeting in Columbiana, Ala. “Sarah Palin cost us control of the Senate.”

Barbara Bush:

“I sat next to her once. Thought she was beautiful," Barbara Bush said. "And she's very happy in Alaska, and I hope she'll stay there."

And a major hit piece in the Weekly Standard. (The author, Matt Labash, may not be an organ of the Republican Party, but the editors are, and it's hard to imagine them having published something like that two years ago.)

Now, Scarborough is correct that elected Republicans, and especially Republican presidential candidates, have shied away from attacking Palin on the record. There's an obvious collective action problem at work. The party as a whole would stand to lose a great deal if she captures the nomination. She runs a good 8 points worse against Obama than against a generic Republican or Mitt Romney. On the other hand, she's popular among Republicans, and a candidate who attacks her would put his own candidacy in grave danger. So the heavy lifting is going to have to reside with Republicans who aren't running for office.