I think it's really weird when it's someone's birthday and they don't tell anyone. A few months ago, it was a coworker's birthday and no one knew all day until her grandmother called and announced she was calling to wish said coworker a happy birthday. Then the news spread like wildfire and we got her a card and a cake (which would not have happened if we had not known). She was somewhat embarrassed and upset (although ultimately pleased by the acknowledgement).
Is it weird that I announce to everyone when my birthday is coming up because I want everyone to know that MY SPECIAL DAY is this COMING MONDAY, OCTOBER 6, 2003?? I just think that one's birthday (Monday, October, 6th) should be celebrated, especially when you start to feel like you are getting old (turning 28 on Monday, October, 6th) and nothing would cheer you up more than a kind word (or perhaps a beautiful boquet of flowers sent to you at work on Monday, October 6th) in recognition of the fact that you were born (on October 6, 1975, 28 years ago this coming Monday, October 6th). So I don't know, maybe I'm the weird one.