I had 3 RMAH sales within hours of being banned. The first one was about 1 hour beforehand and the last one about 2 hours after the ban. The strange thing is that these were my only 3 RMAH sales EVER. I only started botting a few weeks ago and couldn't get my RMAH items to sell for about a week until ban day.
I suspect some people knew they were going to be banned and had a BNET balance that they wanted to use up quickly. They probably tried to buy RMAH items to sell quickly for gold and then sell the gold quickly for USD, or tried to transfer the items to a safe account. I don't know if that strategy would work, though, if there's a delay in them receiving items.
I also thought it might be Blizzard buying my items. The reason is that the 3 sales came out to almost the same as the cost of my 3 banned accounts. This is stupid, though, after some thought. Don't think Blizzard would actually spend money like that, even if I used the money to buy 3 more accounts.
3/3 banned on 12/12/12
Received proceeds from 3 RMAH sales in Paypal today.