Steve keen is one of the few people who was predicting this crisis years ahead. He also comes from a theoretical perspective that explains almost exactly what is happening now (see Hyman Minsky, 1986). This can not be said of most mainstream economists - who work in the neoclassical tradition - who saw absolutely none of this coming. These guys serve little better function than news reporters at the moment. So, I wouldn't be listening to most mainstream economists whose theoretical toolkit is just not suited to the current problems. Hence you still get people whose main concern is inflation arising from loose monetary policy.
Having said that, I think Keen best case scenario is likely. We are seeing unprecendent coordination amongst central banks and intervention in credit markets. The Fed has started lending directly to non-financial firms through the commercial credit markets (this is huge!). The utmost is being done to getting lending going again, and once the credit starts flowing again, the turn around (or more corectly, the stabalisation) will be quite rapid. In other words, the spillover from the financial sector problems to the real economy will be a limited as possible. Keen arguments rely on debt deflations, driving credit crunches and thereby contractions in invesmtent and consumption...this will occur and result in recession (maybe not a severe one in Oz)...but not as much as may have happened in the past due to the historic interventions in the credit markets.
