I ran a couple of tests on the "time based" search results today, to be honest I think it blows. I know for a fact my site has fresh content uploaded over the last 24 hours as it does every day. We rank #2 for our primary term but when I check the last 24 hours I get set of results that don't make sense, internal pages from forums that are not that useful, ebay pages, myspace and some junky directories... Sure they may be from the last 24 hours but I don't see the point if they a poor user experience..