Google Adsense is getting very clever

I was over at XHTML Friends looking at the info for this site and noticed dance ads. At first I didn’t think anything of it, I see dance ads all over this page. But thenof course it occurred to me there is not a single mention of dancing on that page. It gets better when you realise there isn’t even a direct link from that site to this site. I was ready to put it down to coincidence, but noticed ads relevent to the sites I was listing on their pages… That is very clever :) By the way,the site in question doesn’t even need to be displaying Google Adsense themselves (so it’s not even cached ads either; they’re being gnereated live for my site about another site).