That seems to be inherent in the social news set up. Is there any way to account for the time an article was submitted and keep the front page fresh?

Instead of measuring time directly, make a post's "age" for the purposes of ranking be a function of page views. (Or submissions, or something similar.)

I worry that it might be easier to game: refresh a lot of times before submitting to make everything else older. Submissions might work better in that regard, and there are probably other things you can do to mitigate the problem.

That's a pretty terrific idea — and you could make it harder to game by having the page view count be a sum of how many logged in users over a karma threshold had viewed it.

This seems true for all social media sites; use it to your advantage.