As far as I know, all a person gets here when he/she turns 100 is an interview with some local newspaper or news program. No birthday card from the president or state governor.
But it is interesting what they do in England and Australia

I didn't know about that.
Oh, but if a woman here who has already had 6 boys, gives birth to another baby boy, the godfather of the baby is the president, (if the family agrees, of course). I've always found this "tradition" very strange.