I'm torn on this one.
I'm normally of the let'em fail persuasion. However, the US auto industry is pretty darn big (about 5% of GDP). Bankruptcy of GM, Ford and/or Chrysler would be bad. First off is the lost jobs that would occur, then the ripple effects (suppliers, transportation, etc.) of secondary companies going under. Then there is the pensions. Once in bankruptcy, these companies would shed their liabilities to the pensions, and would be transfered to the Pension Guarantee Corp (a federal entity) and the tax payer would pick up the tab (see the steel, airline industries).
GM and Ford, and to a lesser extent Chrysler, have already shed a lot of jobs (MI has the highest unemployment as a result). And are making headway in bringing out new vehicles.
Overall, the big 3 going under would be very bad, and they are all in danger of doing just that within the next year. It's really a question of which would cost more.
And actually, the proposal is for loans backed by the US Gvt, albiet at very low interest rates. Which is probably needed considering the sums the big 3 will need to stay running through 2010 (the credit markets are locked up - see credit crisis.). It's nota bailout in the sense that the gvt is giving them free money.
Personally, if loans are given, I'd like to see the gvt get preferred shares in these companies (to sell at a later date - presuming the stock prices rise). and that the senior management have significant pay cuts for the next X years. That's probably the best outcome. Maybe...