Sep 27, 2010 06:33 GMT  ·  By

Twitter's revenue model was the source of speculation for a long time. The startup said that whatever it ends up doing, it's going to be different and that advertising was the last choice.

It did end up doing advertising, as it turned out, though with a bit of a social twist.

Promoted tweets and promoted trends are supposed to blend in with the regular activity on Twitter and so far, according to the company, they have been quite successful.

For now, both advertising methods are seen as experimental by Twitter, but that's about to change as promoted tweets start showing up in more places than Twitter.com, notably applications and eventually in third-party searches.

According to AdAge, Twitter is targeting November for the extension of promoted tweets to third-platforms. Judging by the response so far, the move should increase revenue for Twitter and provide app makers with a means to make money.

Over the summer, Twitter has run quite a lot of campaigns, for big name advertisers in particular. The company says that the engagement rate on Twitter is significantly higher than that of regular web ads.

Overall, engagement has been at about 5 percent as opposed to 1 percent which is what regular display ads get. Engagement is measured as retweets, new followers and click-throughs.

So far, the results have been encouraging, but Twitter is still somewhat of a boutique option, it has nowhere near the scale search ads or even display ads have on large websites.

Still, with 160 million registered users, more than 100 million active users and reports of about 200 million monthly visitors, Twitter is starting to play with the big boys.

And, for all the reports of a lot of people connecting via third-party apps, the web site is still the main way people interact with Twitter. The revamped site, which is now in testing and is being rolled-out gradually should help even more.

Still, getting promoted tweets into third-party app should increase the ads' reach significantly. Also, app users are going to be more valuable to advertisers probably, since they should be more interested in the medium than the casual visitor.