LinkedIn announced on Thursday it has acquired mobile news aggregation startup Pulse, as Kara Swisher reported last month that it would, signaling another step by the massive professional network toward becoming an online content powerhouse. It’s a big buy for LinkedIn, costing a cool $90 million, according to the company. The app, which collects news articles from a range of topics chosen by users and presents them in a clean, stylish format, rose to the top of Apple’s App Store ranks just a few years ago, quickly becoming a favorite among the many newsreaders currently available. Pulse currently claims more than 30 million users globally who read more than ten million stories daily using the app. But more than that, it’s yet another move by LinkedIn to expand beyond being just a static resume service for recruiters and professionals.