I mentioned this some time back.
SupplyFrame wanted to change from the search bar to their ad based system, which as some people have said, would be more profitable for them.
Unfortunately it means losing the (useful!) search bar, and a bigger ad space (hence the move to the very top, I thought it looked better there, but still not ideal). That's the only size they have apparently.
But I don't see any ads yet, except their own, so it's kinda pointless at the moment.
I have asked what's going on, will see what their response is.
Dave.