Shiva Rajaraman, Twitter product manager announced today that the company is updating its Promoted Tweets functions, making them more personalized, based on user activity.

Launched last April, Promoted Tweets allows advertisers to purchase keywords that will appear on top of the twitter search result. Now, the results will also be based on the brands and people followed by users.

“As we move forward, we are going to implement targeting mechanisms that allow people to engage their audience in that way,” Rajaraman said. “Right now we are starting with essentially keywords but the basic goal is to build out interests based on who you’re following … As that grows to scale, I think we’ll see a lot of opportunities beyond traditional brand advertising.”

It’s a natural progression for Twitter to incorporate more user activity into promoted tweets, which is a form of advertising throughout the microblogging social network.  It’s aim to present more targeted delivery to participating brands is an area Twitter will have to develop as it ramps up its monetization capabilities.  Given the mobile and public aspects of Twitter, increased targeting is something that can be relatively easily achieved, compared to some other social networking entities out there.

Already, Twitter has been finding more ways to layer in personalized and interactive features on the site.  For instance, you can see which of your friends follow a profile you’re currently viewing, as well as other users you both follow.  The new Twitter website is also designed to encourage more social interaction, making it relevant to individuals and less random.