that’s a great idea – works good on how-to posts / product posts, no? same reason why those related posts at the end of the article work so well.

I like it below the article because a number of people will read an article, get an idea and perform a search on a tangent idea right away, so there’s a natural progression to using the search box if it is just below the last place they looked on your blog, the bottom of the article.

In my blog I did the other way around, the search form is safely and conventionally put on the sidebar, but I used absolute positioning on the logo because I didn’t wanted it to perfectly fit the header, I wanted it to spread over the post container as well.