How do bitcoins compare to the cost of electricity? I've got a (fairly modest) Radeon HD 5770, which consumes around 100W under load. At €0.20/kWh, that's €0.48/day (leaving aside the power needed for running the rest of the system). For sake of argument, let's say I can get 2BTC/day with this hardware. Is that worth more than the 48 cents it cost me to do the calculations? (sorry if the answer to this is obvious, I've only heard of bitcoins, never looked into them)
This aside from the moral concern about the environmental impact of wasting energy on pointless hash calculations. I probably waste more energy in other, albeit less obvious ways.
I would be worried about how thin the market is though, as each significant price increase seems to relate to a specific piece in the online tech press. In that way it has a lot in common technically with a pump and dump scheme. As long as you're running a small enough farm I suppose I wouldn't worry too much about it as long as you're philosophically good with the increased energy use.
If it's a waste, than banks computer farms is a waste too.
Sorry, I don't understand this part. I'm pretty sure real currency isn't backed by hash function brute forcing. (I assume they use contracts along with some form of public key cryptographic hashing to sign transactions.)
If mining in a pool, for 5970 it's around 7 BTC/day with the current difficulty. (Unfortunately Nvidia is much slower in integer calculations).
Our mining pool: http://deepbit.net