It looks like the first big name has made an organized jump into Facebook: Wal-Mart.
You too can join the Wal-Mart College '07 group on Facebook. (Facebook registration required)
I did not find the roommate style match quiz to be all that interesting (and it was irrelevant to me, since my wife does not let me decorate.) But I did like their social network piece of allowing you to post your results and send your results to a friend.
Wal-Mart kept up the Facebook wall function so people can leave comments. It will be interesting to see how much Wal-Mart backlash comes from the site as compared to purchases from the links to the Wal-Mart store on the site.
In my Wal-Mart group search, I also quickly found Abolish Walmart!!!, Against Walmart in San Antonio, 6 different Anti-Walmarts, and the Anti-Walmart Coalition. They are vastly out-numbered, but let's see if they are willing to stand up to the experience. General Motors was willing to take the nasty along with the good when they ran their Chevyapprentice.com campaign last year.