Google up inurl:wp-content/1/ [Warning: just google it up, don't visit any of the site in the search results. They are full of activeX viruses!].

What you see is a list of sites that were hacked through the latest WordPress Vulnerability that allows to insert spam into your blog.

Source

http://smackdown.blogsblogsblogs.com/2008/03/23/new-wordpress-233-exploitvulnerability-adds-spam-directory-wp-content1/