While I don't agree with a lot of what twitter has been doing lately, they seem like the only company out there that has a non-gimmicky way of delivering mobile

While I don't agree with a lot of what twitter has been doing lately, they seem like the only company out there that has a non-gimmicky way of delivering mobile ads. If they can actually tune their ad delivery to be relevant to the user--which I think they have a chance of doing better than most--they may actually pull off mobile advertising. If Google can retain the search result screen real estate they also have a chance here--but delivering at most one ad per search. I think that expectations related to advertising revenue will undergo a big adjustment due to mobile. You simply don't have the same amount of screen real estate to display ads on mobile without resorting to gimmicks, and so the overall pie is shrinking rapidly. Email marketing is the one type of marketing that I think still works just as well on mobile--each (opted-in) marketing offer in my email still gets 100% of the screen real estate... and my full attention for a few seconds.