During an informal business meeting at Twitter headquarters in San Francsisco today, CEO Dick Costolo announced that Twitter’s Promoted Tweets advertising platform would be expanded out from Twitter.com to all Twitter clients and platforms.

“Based on engagement rates we’re seeing with promoted tweets, and on the capabilities of revenue team, we’re ready to expand this further,” said Costolo, “Promoted tweets will now go to everywhere that tweets go. Third party platforms, twitter.com and all apps.”

“Our users are super engaged, which is one of the things that we measure constantly. By engagement, we mean that they’re clicking on links in tweets, favoriting things, clicking on profiles, following people. Actions, those are engagement. 40% don’t tweet, but they’re still doing things. The message we hear over and over from brands and small businesses is, the level it is important to pay attention to what’s happenign on twitter is the level of engagement that is there.”

Yesterday, we reported that Twitter is expected to launch its dedicated promoted tweets and trends in the UK within a month or so, and these latest announcements demonstrate that Twitter’s big revenue push will be starting now. Costolo said that Twitter will be focusing on scaling advertising, noting that advertising “is the only thing we need to scale our business”. So, advertising is the way forward for Twitter, though Costolo did say that it may “experiment” with other things here and there.

Costolo gave an interesting analogy, in that the ‘tweet’ is the atomic unit of Twitter. “When we scale promoted tweets, the inventory available to us is monumental”, said Costolo. “Even a super-small volume of promoted tweets to any individual active user will result in a massive scale for us.”

With the traffic that Twitter is generating, Costolo noted that people are realizing, as marketers have for a while, that  engagement is there on Twitter. He cited an example of Radioshack hashtagging #UNEEDANEWPHONE”, and users take their phone into Radioshack to receive a discount on a new phone.

So, Twitter is moving more towards monetization, and Costolo said that growth is at 5% of where it wants to be. To get there, it plans to “offer simplicity in a world of complexity.” This, it seems, means it will look at ways of simplifying the user interface and remove what doesn’t need to be there. “All of these other platforms keep trying to add things”, says Costolo. “And we want to edit ours down.”

Costolo also touched on a lack of BIG data companies for third parties. He cited Dataminr in New York as one example, which analyzes data from tweets.

“Twitter users are more engaged and drive more product and purchases than any other platform”, says Costolo. In fact, we wrote about that a few weeks back, noting that Twitter users are more likely to impact your brand than any other social network.

So, if you’re a super engaged Twitter user you can expect to see more promotional activity across all platforms soon.