2010: The year open source went invisible
The big open source news in 2010 is that open source became essentially invisible. It's not that the media stopped reporting on open source. Far from it. Up until 2010, coverage of open source had remained roughly static, as evidenced by Google News result for "open source" in 2007, 2008, and 2009.
In 2010 that number roughly doubled, but the types of stories changed dramatically. Instead of news of some "hot new startup" applying open source to the exciting world of invoice management, in 2010 we saw open source pervade every area of software, and it became particularly evident in the strategies of web giants like Facebook and Google.
For such companies, open source wasn't a business model, per se. Instead, it became an essential element of a great variety of business models, each baking in open-source complements to drive some form of proprietary value elsewhere. 2010 was the year that open source ceased to be a competitive differentiator for vendors and instead became standard operating procedure for everyone...even Microsoft (though still to a small extent for the Redmond giant).