My guess was that the board was one of a selection being suggested to new joiners as something to follow to get them started on Pinterest.
But from almost the exact day the blog post was published, the phenomenon came to an equally sudden end. In the few days since, new followers have slowed to a trickle (and even fell on one day). Have a look:
Could it be that the Pinterest staffer I tweeted about it, having decided not to reply to me, also decided to end my place in the new-joiner limelight?
That's probably paranoia - I expect they've got better things to do. But I'll be interested to see what happens next.
Other thoughts about Pinterest - by me and others - are gathered here.