One place it appears to live on is at the GM fleet web site, here: http://www.gmfleet.com/
I suppose if you go bankrupt, and then are reborn as a new, lean company, you may want to tinker with your logo. And if you are GM, you want to emphasize each brand individually, instead of reminding people that their Cadillac has something in common with a Daewoo. But the Blue Square dates back to 1964 according to one source I found, and logos should not be thrown around lightly. Remember how Ford was mocked for changing its top line logo from the blue oval to the company name in script?