[alex_c]

In general, the safe choice is to open a link in the same window. I can use the middle mouse button to open the link in a new tab if I want, or I can just click on it, read the contents, and press Back. If you make the link always open in a new tab/window, my options are more limited, and I have to close the tab/window when I'm done, then hunt through my tabs to find your site again and continue reading.

I say "in general", because there might be specific use cases where a new tab/window makes more sense. Maybe you expect the user to want to keep both windows on the screen, or maybe you expect the user to spend a lot of time or drill down deep on the external page. It's hard to say without knowing more, but for a regular social news site, my personal preference is for same window.

[nurall]

Social News is one of the features as I mentioned and for some users it might qualify as just a Social News site based on the way they adopt it but for others the Social News feature might be one of the features they will end up using. Our problem is how do we identify the least common denominator without having to do extensive A/B testing?