suzukik - 6:00 am on Mar 19, 2012 (gmt 0)
Now they will stop requesting a 410 a lot sooner than a 404.
According to a recent tweet from Matt Cutts [twitter.com], they are treating 404/410 eaqually at the moment.
currently 404 and 410 get the same treatment. But folks are looking into whether we should treat differently.