... whose exchange rate against the dollar has gone up by a factor of 6 over the past weeks? If you had any debt nominated in Bitcoin, you'd be screwed.
...which is why you should define debts in terms of some weighted (USD, EUR, Gold, BTC, ...) currency basket and then pay in Bitcoin using its "exchange rate" at that time.
One option: a volume-adjusted average of MtGox.com trades over the last K hours
Another: use 0.001 of the amount to buy options to convert X Bitcoin into the agreed upon amount of (USD, ...). Market-making HFT bots will compete, making X the most fair amount.
All this complexity could be handled by user-friendly software...
You wouldn't be screwed if your business operates in Bitcoins, and your customers pay you in Bitcoins. If you take out a loan for 100 Bitcoins, you will still owe 100 Bitcoins, regardless of the USD exchange rate.
If you aren't dealing in USD, it doesn't matter how much value the USD loses.
Similarly, if you had debt denominated in USD, it wouldn't matter how much value the Zimbabwe Dollar or Weimar Republic Mark lost in hyperinflation. Your debt burden would be the same amount of USD. It just depends on your frame of reference.
The dollar has not reduced in value by a factor of six in the last few weeks. Nearly all of the change in the USD/BTC exchange rate is due to a reevaluation of the real value of bitcoins.
So even if you did all your business in them, it's likely prices would have fallen substantially in the last few weeks, and you would be screwed, per the grandparent.
That said, the source of BTC's volatility right now is precisely the fact that few people are doing business in them, and nearly all demand for them is speculative.
