Those have actually been there for over a year. You're probably only noticing now because supporters didn't use to see them, I dunno why you see it. o.0 Also they're only in the first post.
I was browsing on an iPad which was not mine and was therefore not logged in. It's especially visible on these devices because the screen width is substantially smaller.
Like seeker said, this is a really subpar experience for new users. I get the need for ads, but not when they're moving content out of the way.
Note: those 'first post' ads ONLY show up if you are a) not logged in, b) not registered (i.e. a guest)