The current setup for the "interesting" tab looks at the last 3,000 posts, using various user- and post-specific metrics to display 90 personalized posts; that makes sense, since Stack Overflow gets over twice that every day. We could look at less than that, but...
...At 42 questions per day, Physics.SE's homepage already displays most recent activity on the site... to everyone. The logic used for the "interesting" tab as it's currently set up wouldn't accomplish much.
We've been looking at different ways to customize the homepage; this is still very much experimental, but at some point we hope to have something better than either the current home page or SO's "interesting" tab. Until then...