Previously Jason Calacanis was dumping and now is pumping social networks. In his description about why display ads don't work so well he describes a social setting of hitting on girls and not wanting to be distracted by some ad on the TV, but this is not what it's like participating on MySpace or other social networks. I'm not trying to say that everyone clicks on these ads (personally I use Greasemonkey to remove them entirely) but people do.

His argument is that in "horizontal" networks (i.e. MySpace) there's no way to target the audience while in "virtical" networks (i.e. LinkedIn) it is easy. But I would debate there is as much information about a user in both networks. As a member of LinkedIn you provide such information as: industry, title, previous employers, affiliations, etc. Members of MySpace provide such details as: favorite bands/movies/TV shows/books, age, height, affiliations, schools and BLOGS. Don't forget that places such as MySpace have much more user driven *active* content than LinkedIn. This provices a huge benefit from a marketing perspective.

I think Calacanis understands this as he describes in a future post why Yahoo! purchased Flickr.