After nearly a week, Google seems to have added my site back to their index. I periodically type things like 'romej' and 'steven romej' into Google to see how I rank, and for those particular terms I expect to be at the top of the list. When I dropped off (I couldn't even find my site on the 2nd, 3rd...12th!...results page), I was dumbfounded. I thought maybe I had violated some Term of Service without knowing it.
In their Webmaster section they say:
we find new sites, we lose some sites, and site rankings change.
Knowing that I wasn't new, and that my ranking probably hadn't changed, I figured I got lost due to some quirk or hiccup in the massive crawler and indexer.
Happily, I'm back. Mostly, anyway. Rankings for some search items have indeed changed.