Really nice move from the marketing department of GM to lauch GM Fastlane Blog. As you can see, the comments are open and it's a really nice focus group style. The trackback also give huge visibility to the site.
I'm jalous about the viral spreading of this blog. In less than a week in already have 221 links from 139 sources in Technocrati !
After the IR Report and the Webster Word of the Year, the big company will start to allow some ressources to this (new;-) form of communication really useful to the marketing side of the business.
From my experience, blogging since 2001 in differents forums and collaborative blogs, 90% of my contracts came from my blog posts.