Are high CPM rates for Social Networking App Developers possible?

After reading Justin Smith's Post on Inside Facebook about CPM rates - it got me thinking. I would think that getting advertising dollars would be one of the primary reasons for developing a popular social networking application, so a high eCPM would be the key to monetization. Looking at the huge differences in the values he reported, I wonder why such a disparity exists? Are high CPM rates really achievable by advertising networks resulting in real profits for social networking application developers?

I think high CPM rates are possible - but there are certain things ad networks need to keep in mind.

1) The advertising must be relevant. A teen myspace user looking for some entertainment will not be interested in an ad to purchase furniture. What is relevant usually are ads for other cool applications similar to the app that he/she is currently using.

2) The advertising must be targeted by demographics. The beauty of social networks is the information you have available to you - Use it!

3) The advertising must be targeted by topic. Someone playing a poker game application will probably be interested in a BlackJack game application - and not a celebrity gossip news application. Advertising networks should keep this in mind, and be sure to show that blackjack advertisement more often on that poker application than other ads.

I believe that these social ad networks are evolving slowly - soon they will have figured out the optimal way to serve ads, and I expect average CPM rates to climbs steadily.