I think it's a great idea. Doing it in a platform like Google Calendar, where a lot of folks already belong, makes it an even better (and more extensible) idea. Anything that can put it in more people's everyday path has gotta be a good thing. I don't know what the ideal platform is. Maybe it's Google, maybe it's something else...

I love it! Once we get something set up fo' sure, I'm sure someone would be willing to go back and post all Metachat birthdays to it :-D