A few more details slipping out about Twitter’s advertising plans, it says it will have hundreds of advertisers using its new promotional tweet platform by the fourth quarter.

According to Dick Costolo, chief operating officer at Twitter, the service is looking at big advertising numbers as it tries to live up to his billion plus dollar valuation.

Speaking to Reuters, Costolo, said: “We were valued at over a billion dollars last September, so we’re going to live in a world where we need to be generating hundreds of millions of dollars in revenue. We’re thinking about big, big numbers.”

Costolo said that he believed Twitter would “eventually become profitable”, but gave no timeframe as to when he thought that might be achieved.

Advertising will be one plank of that path to profitability and its business accounts, with additional features, will be another element of that. They are due to launch in late Summer.

The “hundreds of advertisers” it hopes to have means a rapid ramping of the promoted Tweets programme that so far has five on board including NBC Universal-owned Bravo, Starbucks, Sony, Red Bull and Virgin America, which last week gave the thumbs up to Twitter’s new promoted tweets programme after it proved a major hit in helping the airline launch its expansion into Toronto.

“We really look to start to ramp this up aggressively in Q3 and then really blow it open in Q4,” Costolo told Reuters..

While Twitter has said it is very happy at how the tests of promoted tweets have gone Costolo admitted that working with such a small group on the test programme makes it hard to forecast how much of a money spinner promoted tweets could become.

This as Facebook was earlier this week revealed to be the most effective social networking platform for brands to get their marketing messages across to consumers say 80% of companies.

Research said Twitter’s “impersonalised web service” was considered effective by only 45% of brands, according to research.

But serious, this is early doors, let’s see what happens when promoted tweets really gets rolling. That’s going to be interesting. Then we will have something to talk about.