According to this On the Media peace piece, Sign Of The Times, the peace symbol is 50 years old today!

I had always thought the symbol was abstract, but apparently it's a stylization of the semaphore signals for N and D:

The ND stood for nuclear disarmament and the symbol was adopted by a British anti-nuke group. The interview guest gives an interesting little history of the symbol and its move across the Atlantic.

So happy birthday to a 20th century icon!