I won't publish the date, but I too was 50 in early April of this year (it was pretty uneventful).
Much like the stats on the number of postings, I think an age distribution curve would be even more interesting, though of course there is no convenient way to collect that.
I had a birthday this year too - good one, and sorry we missed you, David :-)
Paul - I'm sure the party must have been great, too bad the rest of us couldn't have been there. Maybe you should invite 60 for 60?