Top Blogs are high traffic and need special hosting. whoishostingthis is a web service that tells you web hosting provider by just entering URL of any website. They did a study of hosting providers of top 100 blogs (by Technorati ranking) and here are interesting results.
Blogger / blogspot hosted blogs also featured among top 100. However, wordpress.com blogs were no where to be seen in the list. Click here to see full list and view ofÂ who is hosting which blog!