Of course... if either Nagle or Foo was confident in their predictive ability, they would've shorted btc at 5:1 leverage on Bitcoinica and made a fortune. They can still short if they're confident. But I'm guessing they prefer to make predictions without backing them.
If there had been Bitcoin options in June, offered by a counterparty strong enough to pay off if the price tanked, I would have bought some.
Bitcoinica is only a month old, and already their customers are complaining about troubles getting money out. I wouldn't deal with any options dealer who didn't have a contractual commitment to settle by day T+3. I suspect that a lot of people are going to end up holding the bag when the exchanges shut down.
Bitcoin also had a few 25%+ intra day upward swings on the way down too. Just one or two of those events could have wiped out any position with Bitcoinica.
The market is too small and immature to provide a serious short selling service. I doubt one will thrive with the current volatility.