Twitter, Linkedin and Zynga (makers of Farmville and MafiaWars) have business models that do not rely on advertising.
Marketing and advertising in the future will not be interruptions.. we expect that users will be able to engage with useable content the want to view.
So much opportunity here. Half a billion people on Facebook, 100 million playing Farmville, Movie releases get 5-6 times as much Twitter buzz with an ad.
How are you planning to use online ads for your book or business?