Yahoo offer translate tool http://tools.search.yahoo.com/language/translation/tbTranslatedPage.php?fr=slv1-&lp=xx_en&text=http%3a%2f%2fsearch.yahoo.com%2f I checked one of my pages with ads too and strange thing, there show me ads relevant for translate page. Dont lought at me if this was already discused please. After that i think .. if someone make a page with hight payed keywords and in same page to open a page with adsense what ads will be there ? PS Sorry for my english hope you will understand what i try to say.
It's because the URL Google sees is tools.search.yahoo.com, not your site. Also, Google cannot spider the tools.search.yahoo.com page to see what the content is (as you can see here), so the only "content" Google has to can serve ads with is the URL (which has "translation" in the URL).