As with any advertising, it only makes sense to look at your audience to determine if there is a way to place effective ads. With 200 million twitter users worldwide, it is apparent that a form of advertising would eventually be created here.
In the US alone there has been a steady growth of Twitter users. Put that together with the fact that the increased use of smartphones and even “semi-smart” phones, (those phones that have Twitter access via their wireless carriers proprietary setup), will get more “consumer eyeballs” on Twitters portal, and you definitely have a good platform for niche advertising. -jdognet