Nov 2, 2010 11:07 GMT  ·  By

For the past few months, Twitter has shifted gears when it comes to monetization. It introduced a number of ad units in the "Promoted" family and is now starting to make its biggest move yet, Promoted Tweets in the timeline.

These tweets will only show up in the HootSuite desktop client and only for some users for now, but the plan is to have them available in all clients and on Twitter.com as well.

"When we launched Promoted Tweets in April, we outlined our plan for gradually rolling them out in all of the places people experience Twitter: first in search on Twitter.com, later in search through our partners, and eventually in the user timeline," Twitter said.

"We’ve accomplished the first two steps and, starting today, we are beginning to test syndication of Promoted Tweets in user timelines. Initially, we are testing these with our partner, HootSuite," it announced.

The Promoted Tweets in the timeline are now in the testing phase. Not all HootSuite users will get them and the ones that do will see them in different places, as Twitter tests for the best position.

Twitter emphasizes that this still isn't "ads in the timeline" as the company will match a promoted tweet to a user's interests. The paid tweets will only show in your timeline if the company believes they are relevant to you, just like with all of the other promoted ads.

Promoted Tweets in the timeline will be most similar to Promoted Accounts in terms of determining relevance. While Promoted Tweets in searches show up based on the query, in the timeline they will be picked based on who the users follow, probably also on the tweets they already see and several other factors.

Twitter says that it will only move forward when it's satisfied that the Promoted Tweets in the timeline work as intended and provide value to the users as well. Eventually, they will be rolled out on Twitter.com as well as in any other Twitter client that wants to add a revenue source.