I've been wondering about this. Is AdSense checking IBL? For example, if page A links out some movie websites and has IBL from movie websites, does AdSense display ads related to movies, even if there is basically no word associated to movie in page A?
I would say no. AdSense is designed to be relevant to the page it is on. If you have links to movie sites on the page, it might take those links into consideration, but not the links from movie sites.
But isn't it true that Google creates the map of the website's neighborhood by observing its IBL and outbound links? AdSense is developed by the same people, so isn't there some similarity there?
Same people, but different programs. IBL's etc are used to help determine SERP's. It's the content on your page that determins ad's displayed. It shouldn't matter who you are linking to, it should matter what you are writing about, as that is what is of most interest to your readers.
Yes, I think wendydettmer is right. Choosing AS Ads by links would some kind of stupid - they MIGHT have nothing to do with what's actually written on the page.