One of the most interesting aspects of this crisis is that it is truly a global crisis. This is arguably a first. In historical crises, wars or catastrophes, there is always a large external environment of relative normalcy. Our first real global event will directly impact all economic activity from Botswana to Albany at a relatively granular level. It's even more interesting since the impact of this event is occurring simultaneously in all places at once.
This is a very bad thing. Not only is the information globally dispersed, but it is likely to recast world's economic psychology nearly overnight. Fear, uncertainty, and doubt spread at the speed of light. This has/will cause a substantial decline in demand as people and companies become cautious. Since it is all simultaneous in effect, the cumulative impact will be seen as a comprehensive demand shock (as in rapidly declining demand for goods and services).
If it occurs, this demand shock would quickly hit the global information systems that run the world's companies (they run everything on a just in time basis from finance to inventory). A rapid fall of in demand would likely rapidly translate into a quickly executed -- information technology enabled, so what used to take many months will now take days -- change in corporate behavior. This change in corporate behavior will force cut backs across the board from jobs to purchases to investments. Since it will occur nearly simultaneously (within weeks) of the initial fall of in demand, these cutbacks will be seen as another demand shock and so on.
Since there isn't any stable external environment untouched by the crisis, this may become a uncorrectable and self-reinforcing feedback loop. Also, since most economic statistics have substantial lag, we may not even know it is occurring until we reach the next big tipping point.
Hopefully, the global system isn't as efficient as we designed it to be.
NOTE: Here's an interesting academic paper that looked at whether the great depression of the 20th Century could have been forecast using modern economic techniques/analysis (remember, the depression looked like it was merely a recession when it began). It concludes that it couldn't have been anticipated. It was a black swan.