Last modified: 2008-02-01 03:46:53 UTC
2600+ of them to be precise. See [[Special:DeletedContributions/Ffddd]] for examples, [[Wikipedia:Requests for checkuser/Case/1pixel]] and http://en.wikipedia.org/w/index.php?title=Wikipedia:Administrators%27_noticeboard/Incidents&oldid=188289324#1px_image_DoS_vandal_is_back .
The question is whether there should be some sort of technical restriction on image usage to prevent this from happening again. 500/page might be a good place to start - I have never had a use for that many images even in my work at [[Wikipedia:Featured pictures]].
A denial of service attempt is not a bug. If you want to discuss it, please see the wikitech-l thread.