We’re live at the TechStars demo day in Mountain View, Calif., where companies from the incubator are showing off what they’re up to. Just announced: Intense Debate, a blog commenting plugin system that grew out of Tech Stars, has been bought by Automattic, parent company of blog platform WordPress, for an undisclosed sum.

The Intense Debate system includes commenter profiles, threaded comments, spam control, and other features designed to make the comment sections of online articles more interactive. Rivals include Disqus (which we use) and JS-Kit.

“We started thinking whether we should build it ourselves or buy one of the startups,” says Automattic chief executive Toni Schneider. The two companies were a good match in terms of team style and technology (PHP, MySQL, etc.), he adds. Intense Debate will stay an independent brand, though, and, as before, it will work with both WordPress’s software and other blog platforms.

Intense Debate isn’t disclosing traffic numbers, except to say that it’s been growing 25 percent per month and gets tens of millions of page views. Around 30 percent of blogs using Intense Debate also use WordPress, the company says. It also notes that the forthcoming version of WordPress, version 2.7, will include some commenting features based on Intense Debate, such as threaded comments, and that a new WordPress plugin for Intense Debate is also in the works.

Intense Debate has raised $300,000 from angel investors. The company says it will temporarily be going back into private beta while it works on integration with WordPress.

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