For years, Twitter focused on building a fervent community while other established and burgeoning social networks attempted to do so while fueling growth with advertising dollars. 2011 will go down in history as the year when Twitter was officially promoted from a micro blogging network to a full fledged  interest network, with each of its denizens expressing their likes and dislikes Tweet after Tweet. Combine a highly engaged interest network with the ability to introduce relevant promotions or brands in…