One of the weaknesses I see with bitcoin right now is all the speculating on the dollar value. This doesn't help bitcoin as a currency. It needs to be spent on actual goods and services. If everyone is just in it to sell their coins what use is bitcoin besides kind of a ponzi scheme trying to leave people holding coins when the mt gox value corrects. That's why I setup BitBid. The more people using it as real money the more actual value bitcoin will have.
Is Gold simply a ponzi scheme?
You can't do anything with gold besides make electronic components and trade it as a store of value.
At present: you can't do anything with bitcoins besides make an irreversible transaction and trade it as a store of value.
I don't see much difference.