excellent--thanks for the post, Gemini! I've been trying to convince a few people to avoid the Autobio route--it *is* too busy, and the PS doesn't have enough room to do every subject justice. In the end, the adcomm has nothing memorable to walk away from the PS with.
Along this same line, I've heard that running through all life accomplishments is a no-no; that just reads like an extended resume.
It is best to choose 1-2 events that are symbolic of the direction of one's life/one's accomplishments. Choosing is difficult--that's why I advocate for "kill your darlings." Including *everything* isn't an okay compromise--it's a mistake.
I haven't seen any political essays yet, in the vein of your #3. However, I could see how applicants who are uber-political could write an anti-meat-manifesto, or why-Bush-rocks essay, or save-the-marmoset essay. I suppose this should be qualified, though--if someone worked on a marmoest campaign and did cool s***, that could be appropriate. I'm reading the adcomm's warning as "please don't send us an extended political rant--this a personal statement, not an op-ed."
That said, I've read some pretty smokin' essays here, and those who are really committed to the revision process are doing well, IMHO.
thanks for posting this info!