This is actually a pretty serious problem.
The value of bitcoins always settles such that the cost of the electricity to make them is approximately their value.
But because the difficulty is adjusted such that a fixed number of bitcoins are generated per time (meaning faster or more efficient computers don't help), and that the number generated per unit time is constantly shrinking, it will cost more and more electricity over time to make bitcoins.
Deflation is built into it. And I bet the creator of bitcoins never realized that the scarce resource bitcoins track is electricity.
If you want to make a ton of money, buy bitcoins just before they switch from 50 per block to 25. I'm betting the value will double.