One can argue that when it comes to marketing, the two eras can be classified as the one before FB came about and the one after @facebook came about. The inflection point, probably lies somewhere around 2009, by the time FB had a critical mass of users to begin drawing useful inferences from.
Has there been a study that has been done that measures the efficiencies that the FB personalized marketing behemoth brought about for organizations. Both big and small. Would be especially interesting to understand, how this has helped smaller companies, both in getting customers much much quicker and also in effecting the marketing spend as a % of revenue. How have the corp marketing budgets shifted from completely offline to a mix of offline and online?