Here's an invite that certainly wasn't shared with me on Facebook: The social network is having its holiday party tomorrow evening at Bay Meadows. Bay Meadows? The San Mateo venue strikes me as about as far as you can get from the hot startup's still edgy self-image, defined by the commissioned graffiti on its walls. A racetrack clubhouse is where it's spending some of the $300 million it just raised from Microsoft and Hong Kong billionaire Li Ka-Shing. Perhaps Facebook's employees are aging even faster than we thought.