Via the Washington Times:

Ms. Fey’s first appearance as Ms. Palin, on the premiere episode of the show’s 34th season, became NBC.com’s most-watched video ever, getting nearly 6 million views in a few days. A month later, on Oct. 18, she appeared on the show alongside the real Sarah Palin; the pair was responsible for the best-rated “SNL” in 14 years.
Impressive work. But in “Bossypants,” Ms. Fey has only complaints. Her parody made her a “lightning rod” and garnered her “hate mail.” The writer-actress who became the first female head writer on “SNL” thinks sexism contributed to the reaction.
“No one ever said it was ‘mean’ when Chevy Chase played Gerald Ford falling down all the time. No one ever accused Dana Carvey or Darrell Hammond or Dan Akroyd of ‘going too far’ in their political impressions. You see what I’m getting at here,” Ms. Fey writes.