This, combined with a burying system to get rid of junk stories, could clean up the 'new' section substantially. It would also be useful to factor snr into the computation; the nature of the karma system, which makes it more advantageous (at a marginal level) to submit a story than a comment, encourages a shot-gun approach to submission; SNR would combat that.
EDIT: Ha, points to jwecker for posting about SNR while I was writing about it.
I've never used Digg, but from what I read of them, their burying system is working out rather poorly. Burying a story on Digg requires an O(1) number of votes, so anything controversial gets buried even if 90% of users agree that it's an excellent article. A simple up/down model like Reddit's seems like a better idea, but see the top-level comment that I'll have posted in about two minutes.
EDIT: Ha, points to jwecker for posting about SNR while I was writing about it.