It's a three day race to see who can finish the entire Monkey Island series in the shortest amount of time. Here are the threads for the last two races:
The Great Monkey Island Race of 2009
The Second Great Monkey Island Race of 2009
Here's a brief history. Before chapter 5 came out, there was a thread encouraging people to run the series in a marathon the day before the game came out. Then someone said that somebody should stream it over the internet. I accepted the challenge, and while I was testing the streaming software, Icedhope and I decided to make a race of it. Iced, Secret Fawful, and I were the only three participants, and nobody finished. I played for 18 hours straight and only got into the start of Tales, if I recall.
So after chapter 8 came out, more people were interested in participating, so we held a second race at the end of December. This one was more well-thought, and we spread it over three days. OzzieMonkey won (by five freaking hours, wtf?), I took second, and apenpaap took third.