Yuri's Night 2007

What?  There's an annual, geek-related, anniversary celebration that I didn't know about?  For shame!

From GMSV:

On this day in 1961, 27-year-old Yuri Gagarin lifted off the launch pad in Baikonur, made a single, 108-minute orbit around the Earth, then rode his capsule to a parachute landing on the Russian plains, becoming the first human to venture into space. There is obviously only one truly appropriate way to mark this historic event — tech rave! In cities around the world tonight and tomorrow night, Yuri's Night '07 will be celebrated in parties that will be mashups of science and art.