@Steve 41oo,
Did you support the UK government's bailout of Northern Rock????
In general, governments intervene to protect the public interest when it is affected, as opposed to the interests of investors in the failed banks or corporations. Individual cases are often arguable, and finding a clear line between the public interest and those of investors is often very difficult. However, overall I believe the actions taken (and not taken) in the cases of Bear Stearns, Lehman and AIG are, so far at least, appropriate.
Overall these interventions are tame compared to the various nationalizations of transportation systems and "industrial champions" that have long prevailed in Europe.