We notice some changes too since june, you think it's too push people to buy adwords? I feel too that small websites have trouble to rank against bigger ones.
This is no conspiracy. Ignoring that larger sites have better page rank, they can also spend more on SEO.
Ma and Pop's widget shop is a wordpress clunker built by their teen son. He's not spending 20 hours a week watching metrics and messing with SEO. $big_shop_webmaster certainly is.
> And WordPress is professionally written software.
So are many web servers, why would this affect ranking? Content, not platform should be the determiner (though some hosted content might get penalized because of others using the same host).