A month ago, it was reported that LinkedIn was in negotiations to buy Pulse. Now, it’s official: the popular professional networking site has acquired the popular news reading app.

According to AllThingsD, the acquisition was agreed upon to the tune of $90 million.

LinkedIn and Pulse apparently make an unlikely pair. But the acquisition actually goes toward the former’s goal of becoming, as LinkedIn SVP of Products and User Experience Deep Nishar puts it, “the definitive professional publishing platform — where all professionals come to consume content and where publishers come to share their content.”

For its part, the Pulse team says that “LinkedIn is the perfect partner as we continue our journey. The company shares our passions and values, our belief in the power of knowledge and elevated discussion, particularly for professionals looking for insights to help make them better at what they do.”

The Pulse team has also announced the addition of a new Linked Influencers feed in the Pulse app, enabling you to read posts by well-known thought leaders. But the team suggests that the app will remain significantly unchanged for the time being.

Released as an iPad-only app in May 2010, Pulse later launched on iPhone and is now available as Android and Web apps as well. It now has more than 30 million users.

Compatible with iPhone, iPod touch, and iPad running iOS 5.0 or later, Pulse is available in the App Store for free.