I don't mean to take a stab at any happy bubble, but basically 50 000 is a number no more and no less. The air won't taste any better or worse when we reach it. But competition to reach a given number of posts or to be the one who posts the message with a particular number doesn't seem like the best idea. I have seen boards where piles of useless stuff (good old "word association game"

:) were posted just for the sake of a number. I hope I'm not too much of a killjoy, but I will value a 49999th or 50001th message with some content, and some point much higher than a:
"YEAHH 50000 I REACHED IT! I DID IT!!! THIS IS SO COOL!!!" kind of message -_-