Would love to trash it (got it way back, when it was Harvard-only), but it's how I keep track of my kids' online activities. (Though I admittedly only check once every month or so...)
Just a few days ago. I wasn't very active, and never really got into it. I would have left it inactive, but the privacy-related discussions convinced me to shut it down.
I deleted my account three weeks ago, just before the media went nuts over it.
I just did, with Twitter, FoRK, Buzz, and I think I'll deactivate YC too.