is there any kind of financial agreement behind this kind of thing? are google paying something to stack overflow to compensate for the extra load, or are s.o.

is there any kind of financial agreement behind this kind of thing? are google paying something to stack overflow to compensate for the extra load, or are s.o. happy to have the extra traffic / eyeballs? maybe they are going to be a sponsor or whatever it is that gets an icon displayed? and if it's "free" is there discussion beforehand, or it is just assumed that s.o. will handle things? not trying to imply anything, just curious how shifts like this, which could be significant in terms of extra load, are arranged.