The GitHub t-shirts distributed at RailsConf 2008 were highly popular, featuring a playful design with "fork you" on the front and a customizable space for GitHub usernames on the back. Attendees were encouraged to personalize their shirts using permanent ink to display their usernames proudly. The event included notable figures such as Thomas Fuchs posing with a large octocat mascot, and the t-shirts were made possible with the assistance of Ryan Norbauer from rubyrags.com. The shirts, celebrated for their creativity, are set to be made available for purchase soon. Tom Preston-Werner, co-founder of GitHub, authored the announcement.