Yahoo! Hack Day is an event where any developer can participate in a 24 hour event that begins on September 29, 2006. There is room for 500 hackers and 100 total projects. People attending Hack Day can camp out at the Yahoo! headquarters.

The coding ends at 2:30PM on Saturday, September 30. Every team then pitches their demos to the judge panel. There will be a musical performance by a special unannounced guest as well.

There will be speakers with a strong background on web applications as well such as Rasmus Lerdorf (creator of PHP), Andy Baio and Gordon Luk (co-founders of Upcoming.org), Cal Henderson (engineering manager of Flickr.com), and a keynote by Bradley Horowitz (head of product strategy of Yahoo!)