First I want to say I like that the website looks clean and neat. I can't stand going to news sites and everything is jumbled and cluttered. So thank you for that.

I agree that images with the articles would be helpful. If you are using Rails then the masonry gem may be handy.

Maybe use general OAuth rather than Twitter specific. I don't see a reason not to include Facebook.

Like the Opinion section. Maybe have some friends start seeding it with content to encourage people to use it (seed it with good content of course). Will you be allowing comments on the Opinion pieces?

Good choice to make links open in a new window! That's a pet peeve of mine. It makes the user experience better when they don't have to keep clicking or swiping back to use your site.