Assuming you kept your WordPress installation up-to-date, you probably ran into trouble thanks to an insecure plugin or theme. I recently ran into exactly the

Assuming you kept your WordPress installation up-to-date, you probably ran into trouble thanks to an insecure plugin or theme. I recently ran into exactly the same exploit because I had a deactivated, older version of the Thesis theme lying around in my themes folder, which contained an old, insecure copy of TimThumb. Restoring to a pre-exploit backup and then removing the offending, no-longer-needed theme seemed to do the trick. While WordPress.com offers better security than Dreamhost, they do this by restricting your choice of plugins and themes - you'll be more secure there, but you'll have less freedom. I suspect any place that lets you run with arbitrary themes and plugins will have similar issues as Dreamhost.