Don't think that is an accurate statement.
I don't believe it is, either. She recorded a campaign commercial for him that was played ad infinitum, according to AZ freepers, but that's all I'm aware of.
For the record, back when we here in Texas had our gubernatorial primary some months back, Dick Cheney's recorded pitch for Kaye Bailey Hutchison (RINO-TX) ran day and night for weeks on end.
I also hated to see Sarah endorse McCain, but I'm grown up enough to understand why she had to do it. Now that she's repaid her political debt to him, she's free to push forward and help every real conservative she can.
She appeared at TWO campaign rallies for McCain in March 2010, at least one of which was streamed over the Internet. [Note that J.D. was already in the race at this point in time.]
LIVE THREAD: Sarah Palin at McCain Rally NOW ("Send the maverick back to the United States Senate!")
AZ-Sen. 2010: Palin Makes Fans Uneasy by Backing McCain (McCain wants to co-opt Tea Party)
She also went on at least one live television interview with Fox in which she said that McCain is part of the Tea Party.
Palin: Tea Party Leaders Agree with McCain on Big Picture
She also wrote an op-ed piece for The Arizona Republic imploring Arizonans to re-elect McCain.
AZ-Sen. 2010: A desire to serve defines McCain (Palin begs Arizonans to vote for McCain!) (BARF)
On top of that, she not only recorded those campaign commercials that were "played ad infinitum," but she attended at least one reception/dinner with photo op to raise money for McCain, not that he really needed any more since he had tens of millions left over from 2008 (that he refused to deploy against Obama).
AZ-Sen. 2010: Reception and Dinner with Governor Sarah Palin (raising money for RINO McCain!)