the explosion of nastiness has been something to behold

Yup.

the rise, fall, and departure of Sarah Palin

What?
She is still rising.
She has not fallen.
And I do not believe she is departing.

I agree with you somewhat. I don't think there has been any fall as of yet, and I am not even trying to guess if she is departing or not.

But the main point is that the left has brought politics down another notch from which it may never recover. Kids are fair game now. I won't be attacking them myself, but I also won't be able to sympathize with those on the left who will squeal like stuck pigs when it happens to one of their own. It will really be hard to sink any lower than those who defended child rape jokes, disability attacks, and hate rape lists.