Twitter has added nine members to the "Certified Products" partner program it created last year, bringing the total number to 21. The program is still missing an "Ads" badge that would allow designated vendors to bring new sources of demand to Twitter's Promoted Products. For now, partners are still grouped into the original three categories: Analytics Providers, Data Resellers, and Engagement companies.

But a partner status for Twitter paid media (i.e. Promoted Products) may be in the offing, in the form of either an Advertising API program or a real-time bidding platform such as the Facebook Exchange. One reason to think so: Twitter has hired Zach Hofer-Shall to manage the partner program. His job description, in addition to managing partners and vetting in-bound applications, includes, "building out new verticals to accompany the current categories."

Also interesting: Twitter has anointed Adobe, a large player in display and social advertising, as one of the new Certified vendors its Engagement and Analytics categories. Twitter says, "Adobe Social, with its deep integration in the Adobe Marketing Cloud, allows marketers to understand how their Tweets drive value."

Here's what Twitter has to say about the other new members of its Certified Products Program, from its blog post:

• Shoutlet, Spredfast and Sprout Social make it easier for large and small businesses to manage their Twitter presence -- for example, by allowing multiple team members to respond to customer’s Tweets from one Twitter account.
• Percolate and Rallyverse help brands create meaningful and engaging Tweets.
• Sysomos, Simply Measured and Visible Technologies build analytics products that help companies better.