This is how Ford does it

This is a good blog post on how Ford utilizes social media in its promotional efforts --
http://www.clickz.com/3635034

Buying Facebook friends & Twitter followers

I'm not sure what I think of the practice described in this blog post:
http://www.economist.com/displaystory.cfm?story_id=14460087&fsrc=nwl

Ford, Papa Johns, Levi Strauss & Chevron use social media in their promotion mixes

This Courier Journal article addresses how Ford, Papa Johns, Levi Strauss, and Chevron are incorporting social media into their promotion mixes --
http://www.courier-journal.com/article/20090919/BUSINESS/909190352/-1/Category=search