This is a slightly updated/cleaned up version of 2778890 -- It adds the "-t" option to fsdiff which ignores files where only the timestamp has changed.
This patch has been floating around for a long time and I've been using it in production with no ill effects - I'd very much like to see it become part of the official feature set.
Patch (git format-patch) against git master/head 20120203
I also would very much like to see this option merged into fsdiff. Updating timestamps is a big waste of server space and time.