Twitter is believed to be planning a new advertising system similar to Google's AdWords.
According to a report in the Wall Street Journal's All Things Digital blog, ads will be targeted on the basis of Twitter searches.
They will be displayed in the same 140-character format as normal Twitter posts, though they won’t appear in users’ regular streams.
The only direct ads to appear on Twitter at present are small text adverts on user home pages - although third party apps sometimes include ads themselves.
According to the WSJ, the new plan envisages distribution via third-party software, with suppliers sharing the ad revenue with Twitter itself. Ads would initially be sold via agencies, with the company later moving to a self-service model like Google and Facebook.
Twitter needs to find some way of making money - it's ruled out the idea of charging either for the service itself, or for its API.
The service could launch by this summer.
Meanwhile, Twitter API developer Alex Payne has got people a-twitter by saying on his blog: "If you had some of the nifty site features that we Twitter employees have, you might not want to use a desktop client. (You will soon.)"
But he's denied this means that third party developers have anything to worry about, adding: "Uh, everything I like that’s on the employees-only beta site is actually *built* on public API methods we’ve already given developers."