A bit of knowledge to amaze your your friends with at parties:
"The peace symbol was born from the flag positions that represent the letters 'N' and 'D' used to communicate nuclear disarmament. Gerald Holtom, a graphic designer who figured that the British anti-nuke movement would gain more traction if it had a logo, settled on this final approach and the symbol was developed."
Huh! How 'bout that.
Read more about it on Symblogogy, posted when the peace symbol turned 50 back in March.