When acquisitions won't do, the company plays hardball. Last year it disabled access to its API for mobile Twitter tools developed by UberMedia because of violations to its API agreement. And this summer Twitter stopped allowing users to share tweets on their LinkedIn pages. The company said on a blog post that it is increasingly focused on “providing the core Twitter consumption experience through a consistent set of products and tools.” Its latest announcement about officially recognized third-party developers falls into the consistency category. “Twitter's certification is an acknowledgement that the social products we offer bring value to marketers that perhaps are not being addressed by social networks natively,” Margaret Francis, VP-social products at email marketing company ExactTarget told Social Media Marketer. “It's a wonderful sign of Twitter's maturity.” The certification program made no mention of UberMedia's Echofon or Tapbots' Tweetbot, possibly because they mimic the main Twitter software too closely. And a large number of favorite b-to-b social monitoring tools also are conspicuously absent. According to a recent study by BtoB, “Social Media Marketing: A Surge in Adoption,” a significant number of b-to-b marketers use tools such as Crowdbooster, HubSpot, Scout Labs, Social Mention, Sysomos, Trackur and Tweetburner. While it seems likely that those companies could apply for inclusion in Twitter's approved pantheon of third-party apps in the future, its current stance seems more about preserving and extending its hegemony than about marketer preferences and application usefulness. Michael Lee at ZDNet has written a good recent overview of Twitter's developer strictures. For now, Twitter will continue to provide a free API to third-party developers, according to this report by Poynter Institute blogger Craig Silverman. While marketers may find Twitter's new certification of API partners helpful in screening for appropriate tools and clearing up “confusion,” but as is clear from BtoB's social media study, marketers have already developed personal favorites based on their own needs and the recommendations of peers. Christopher Hosford is east coast bureau chief of BtoB (www.btobonline.com). He can be reached at email@example.com.