The Shift Communications website and their blog, PR Squared, offers loads of (free) insights, template, etc. about this topic. You can find their Social Media Press Release template here. And updates are discussed here and here. Furthermore, you'll find the Social Media Newsroom template here.
Following their blog you see that many companies aren't getting this yet and are releasing news in the traditional way. The examples that are given are inspiring nonetheless. I like the remark that was made stating: "...the social media press release in really nothing more than a blog post".