Hold your horses!! The overwhelming fraction of those 2 million bitcoins are people sending money to themselves. The way the Bitcoin client works, if you want to send 42.53 BTC to someone, and all you have is an address with 41689.32 BTC, then you have to send *all* the 41689.32 BTC out, then split it into 42.53 BTC for your recipient and 41646.79 BTC back to yourself:
Thank you for the clarification of that point, Patvarilly. That does change things quite a bit. I was wondering why the number of bitcoins sent each day was so much higher than the number traded on MtGox and the other exchanges.