Twitter is ready to roll out retargeted ads fueled by browser cookies, sources confirm. Twitter has announced the program, expanding retargeted ads beyond the “experimental” phase that started in July. The secret sauce of Twitter’s retargeting is the use of your account as a cross-device identity layer, allowing it to target ads on mobile based on where you’ve been on the web. Some details of the announcement are hazy. It’s said to be somewhat of a “soft launch” in that all advertisers might not be immediately eligible to buy the ads, and they might not show up to all users. Retargeted Promoted Tweet ads will almost surely become available for purchase, though it’s unclear if Promoted Accounts will, too. I haven’t heard whether Twitter will be expanding email address retargeting either. Twitter declined to comment on this story.