If Facebook's ultimate objective is to be purchased, monetizing may be counterproductive if it renders the site less attractive to a purchaser. Realistically, no one is going to buy Facebook (at the valuation they want) based on its revenue-generating potential.

early adopter under-30s have become impervious to web advertising. the clickthrough rates are just dismal. yahoo and aol cater to the trailing edge...you know, the people dumb enough to click a banner ad. thats why they make money with content (non-search) ads.

fb should consider a nominal monthly fee for advanced features (a la flickr). my guess is that the service has become sticky enough to turn the screws ever so slightly on users. barring a subscription, i don't see them ever making a lot of money....unless they just go to a cpm model and advertisers just give up on clickthrough

it's easy to make enough to keep it sustained

a bit harder to make money off it

and almost impossible to make the kind of money they are EXPECTING to make off it (see company valuation)

it was overhyped and now it will struggle to meet the expectations of its investors