We went from our normal rate of 5k bookmark writes per day to over 5 million in a 24 hour period without going offline.
Hell, we didn't even get slow. Our median page load times stayed well under a third of a second. We had no advance notice of the announcement and had to handle the spike in traffic on the fly, on one server. Our competitors crashed, we stayed up.
I'm pretty proud of this and I think our users got their money's worth from Pinboard today.