Another notable PSC milestone (which came to memory thanks to Volkswes's comment on this thread) is this entry:
http://photoshopcontest.com/view-entry/30937/croc-eye.html
This was a winning entry from a daily contest in 2003. Up until that time, most winning entries were lucky to garner 30-50 votes. Volkswes shattered all existing records for the time by racking up 82 votes which was unheard of for the time. As Wes mentioned there was no advantage during that period and speed was as much of a factor as skill.
During that time the daily image was revealed each morning at 8 a.m. If a PSC user did not have an image submitted by early afternoon/evening - no matter how good - it would likely not land on the front page and ultimately suffer from low exposure and voting.
Although I'm not sure how long Volkswes's record stood, I believe it was for over a year.