Palin was McCain's canary in a coal mine.

Come to find out, "palling around with terrorists" was a line fed to Palin by the top of the McCain campaign. They wanted her to use it, and they had a campaign ad waiting to follow about a week behind her introducing that hard Ayers attack.

It appears that upon seeing the reaction, the McCain folks decided to pull back, leaving Palin twisting on the "terrorist" limb.

Of course, that's just one version of the story told by one side. (But it does explain the raging animosity the Palin folks have for Nicole Wallace.)