Yes, that’s right, you math nerds. March 14 is Pi day.
From Wikipedia:
The mathematical constant Ï€ is an irrational real number, approximately equal to 3.14159, which is the ratio of a circle’s circumference to its diameter in Euclidean geometry, and has many uses in mathematics, physics, and engineering. It is also known as Archimedes’ constant (not to be confused with an Archimedes number) and as Ludolph’s number.
Update 15/3/2007 – Saw this on Digg, explanation about how the constant Pi is used! Very informative stuff: http://www.howstuffworks.com/pi.htm