Perhaps CNN is considered mainstream media only in the USA?
Unless you've got Satalite TV (and not always even then) CNN is generally not available outside the US.
But regardless. Getting realtime updates from first hand accounts verses a condensed chopped and shaped versions once maybe every hour wins every time.
I have to say though that before this I'd never even considered Twitter to be more then a geek toy. Then you have NBC reading direct quotes from it...