I looked and didn't see any post related to the day's celebrations. Kinda shocked to be honest.
For those unaware of what Festivus is you can find out more about the holiday here.
Or you can save some time and watch the story of Festivus.
And here's a slightly longer (and way better quality) clip from that same episode, which features more of the things that resulted from George's embracing of Festivus.
Let the airing of grievances and feats of strength begin!
EDIT: Here are two you may dole out for the season.