I have a couple more hours, but so far I'd say my Kindleboards banner didn't do much good, at least in a direct way. I've sold seven copies of Unwrapped today-- this month, the average up to today has been nine per day-- and my ranking has dropped from #1910 before the ad went up last night to #3628 tonight. (#1910 is unusually good for the book, however, and I don't know what caused that little spike. I think it's at a more typical ranking now.)
So the KB ad had no effect that I could see. However, most of my books have been pretty limp today, saleswise, so it's possible people just are too busy today cooking or traveling to buy. And there's never any harm in getting your name out there in front of people... it might sell more books later, for all I know. Still, I thought I'd post my results, or lack thereof *g*, for those who are interested.