First off, allow me to say how impressed I am at the robustness and usefulness of Newsvine even at this still early stage. Already it's taken a top spot in my bookmark bar, along with Bloglines, Gmail, and Flickr. It's truly a shining example of what you can do on the web these days - but there's still something missing, and I want to formally request a feature.
The only other collaborative news site that left much of an impression on me was NowPublic, which I became aware of not for their textual news, but their photojournalism features. Living in NYC, I'm occasionally finding myself blocks away from breaking news stories. I took a handful of photos during the aftermath of the British Consulate "bombing" back in May; I also uploaded them as "coverage" to NowPublic to help flesh out their story.
I would love to see similar functions on Newsvine - to pull photos from other sources (preferably my own flickr pool, but wherever) and attach them to a story, like comments. The possibilities for end-user photojournalism combined with the chat rooms on breaking stories could lead to some really powerful results.