This has been an amazingly misleading news story across the major news outlets. There is an issue with one (not even the largest one) exchange and all the news headlines make it sounds as if the value of Bitcoins across the world have fallen to zero (current value is roughly 700 USD per Bitcoin).
Essentially, the Mt. Gox exchange currently wont allow user to withdraw Bitcoin, but it will allow them to withdraw the equivalent value in fiat currencies as they work out their issue.
I am not a big follower of Bitcoin, but the spin on this story has been amusing to watch.