I've written about GM and their chances of defaulting a few times.

http://www.noelwatson.com/blog/PermaLink,guid,7f056791-b34d-4d40-9554-ad772079878f.aspx

http://www.noelwatson.com/blog/PermaLink,guid,49d6809c-0c1b-4dc4-8e4e-d15ad9acb209.aspx

http://www.noelwatson.com/blog/PermaLink,guid,a5cd0517-0d1c-41e6-9bfc-f379327afb93.aspx

However, it seems like things could be turning around - it will be interesting to see whether a tie up with Nissan and Renault occurs

http://www.bloomberg.com/apps/news?pid=20601087&sid=aywBCTuUnDFg&refer=worldwide_news

GM appear frequently on Markit's daily email for greatest credit improvement, and the 5 year CDS is now around 700bps, almost half of what it was at the peak.