Facebook tries too hard to monetise?

The evidence is surely growing that Facebook is trying too hard to monetise the relationships on the social network as it approaches its IPO and may damage the product.  Sir Martin Sorrell is probably right when he has advised organisations to be cautious about it as an advertising medium  rating it more highly for PR activity.  Are PR consultancies and in-house PR teams leading Facebook activity by organisations and major brands; or are marketing teams heading this up or a third way with major brands developing cross-disciplinary teams including customer service?