I find myself resorting to 'Show Search Tools' -> 'Past x' more and more frequently these days. As the web ages, it seems the proportion of old and potentially outdated information in Google's index to new information is increasing.
While Google Instant is technically impressive, the feeling of speed is undone whenever I have to next manually restrict the results to the past year or 6 months or whatever (and sometimes experiment with multiple durations) in order to filter out discussions from 2008 and earlier. Same with using regular search as well.
Hence, might I suggest you guys consider something like inverting the default search, to only include pages created or modified within the past year (or whatever duration you calculate most optimal for returning relevant results)? Or perhaps changing the PageRank weighting of recency, at least for domains that change rapidly. I know this could cause some problems, and I'm not sure the web is quite at the age where this is necessary yet, but I think there's an inflection point coming soon where more searchers will expect recent results in their top 10 rather than years-old pages.
It might also be worth moving the duration filter up one tier of UI so it is both clearly visible on the search results page, only takes one instead of two clicks to activate. The OP isn't the only one who's recently needed searches restricted by age and didn't realize just from the UI that this could be done. A few months ago I made a similar complaint on another forum and was informed of the same thing - use Search Tools -> Past X. But it's not obvious to do that on the current UI.