You can't really pin the blame on any one thing:
Gordon Brown was/is an incompetent fool, selling the country's gold reserves at an all time low, failing as chancellor to do anything about a rapidly expanding credit bubble that was fairly obviously going to cause a problem at some point down the line, and since being in charge he's ploughed a lot of money at a problem and generally failed to do a huge amount,
Bankers, got far far too greedy and lending out lots of money with very little security on that loan because they could sell that debt on and make more and more money, even when they were buying up this debt, much of it 'toxic' from other banks themselves, just plain dumb.
Corporations, running a business model that relies so heavily on debt, no wonder then we've seen so many businesses fail really.
People, yes, the general public, the idiots who bought into the idea of ever increasing house prices, who thought that 10x income multiples of 125% of the value of the house was a good thing, who thought that it was sustainable to live your entire lives on credit cards, hire purchase and finance.
With regards to the government, would the tories have done any better? we'll never know. Could and more importantly *should* the labour party have done better, hell yes.
Banks, frankly I think brown/darling should do some fairly hefty steps here. It looks like RBS and possibly Barclays are in a dire situation, why not draw a line under them, nationalise at least RBS, sack the idiot directors with no redundancy/retirement/a single penny, let the people with savings withdraw their money. Then do a full accounting of the loans outstanding, those that are worth anything sell on, those that aren't (and I think this might be the majority), then effectively right off the losses on them. Yes it would cost a lot, but it would draw a line under RBS and let the other banks know that this could well happen to them.
Corporations, not sure here, if they were dumb enough to run in a manner that was entirely dependant on credit then should we bother to save them?
People, I don't want my tax money going to help out the feckless frankly, if they got themselves into an unsustainable amount of debt then they can declare themselves bankrupt and lose their house, wouldn't bother me one bit.