Marketers have not warmed to social networks. The advertising that Facebook and MySpace get tends to be at low cost per thousand compared with the advertising on large content sites like CNN, while Twitter gets almost no advertising revenue at all. Marketers find it difficult to use huge, disparate pools of people to effectively reach specific demographic targets. Facebook may have 200 million members by some counts, but its revenue is only about $500 million a year.

The FT reports that retailers have been making a marketing surge on the large social networks this holiday. The paper reports "retailers have reinforced their traditional efforts with an array of new social-networking weapons including Twitter, the micro-blogging website." Best Buy (BBY) released its sales discount information early to one million Facebook "friends," and it's also using Twitter to send information about its deals.

Most large retailers will follow the pattern of getting out their discount information early and often on the three large social networks. The results of the effort may end up being more important to Twitter, Facebook, and MySpace than they are to the retailers themselves, if that's possible.

If the figures show that social network marketing did very little to lift holiday sales, the conventional wisdom about the ineffectiveness of the medium to deliver advertising results will have been bolstered, and it may take Facebook, Twitter, and MySpace a long time to recover from the failure. On the other hand, if they deliver the goods on Black Friday, it should cause the largest retail markets to invest very substantial sums in social media in 2010.

Douglas A. McIntyre is an editor at 24/7 Wall St.