There is a load of history and science behind it all, though without getting geeky, wiki has a pretty calm explanation of it.
Concert pitch - Wikipedia, the free encyclopedia
In high school, we used 440. At BSU, we used 440. In Vegas, we used 442. 442 has a "brighter" sound which some claim is more brilliant in color and character. Personally, the 432 is far more desirable. The problem with this, is that percussion instruments (marimba, xylophone, vibes, etc...) are pitched to 440 or 442, and your group needs to tune to whatever those are, since they cannot change. Perhaps there will be 432 offerings in the near future, as I know I will shift my entire program towards it if I can get those.