[gfaremil]

From engineering point of view, the sad thing (and danger) about Google, Twitter, or Facebook is they will get in trouble as soon as some other company figure outs more efficient advertising model (and starts eating their revenue).

In other words, regardless of all these great things Google is doing and great technology, if somebody invents better ad market than AdSense, all this great technology will not help them at all. That is the problem.