We knew something like this was coming. Twitter couldn't get by forever just showing advertising on the website. A Twitter developer advocate has confirmed that changes are being made in the API to insert ads automatically into the stream. The system is set t o be beta tested with a small group of developers before a wide scale rollout. The developers of Twitter clients like Tweetdeck and Seesmic will get a share of this ad revenue, but no exact values have been decided.
Twitter's limited use of advertising has, thus far, caused little objection. The trick will be getting enough ads in place to turn a profit, without alienating users. As for the developers, some of them stand to make quite the handy payday from this arrangement. Twitter has not clarified if displaying the ads from the API will be voluntary or not. Would you accept ads in your Twitter stream if it meant the developer got paid?