GoogleBot has said to delete almost all the pages of the Webmaster World site. How? Here is the story. It said that the Webmaster Site was reconstructed a few months back putting all the content into a database driven solution. But, the main mistake was made when, while publishing the new site, an employee of Webmaster World left the "Edit" link open on the frontend, where GoogleBot can easily reach it. It is presumed that the site was not protected with a password and therefore became victim of GoogleBot. Visit The Daily WTF forum for a complete picture.
As GoogleBot just clicks on links, in the same way it also clicked on the left-open delete link on every single page of the site till the whole site got deleted from its database. I think its a simple case of irresponsibilty, for which GoogleBot cannot be held responsible.