Sony Ericsson lets you create a virtual Christmas tree that features pictures of you and your (Facebook) friends that appears once you wave your mobile phone in front of a web camera. Though shown working with a Sony Ericsson phone, it probably works with any mobile phone, as long as its screen is bright enough:
ARWishes, on the other hand, is a web application from Inglobe Technologies (of AR-media fame) that lets you attach holiday related 3d animation to holiday related AR markers and send them as a greeting card to your friends:
ARWishes is not focused solely on Christmas greeting cards, and is set to capture the augmented reality greeting cards market (yeah, I made that up). It already features some new-year and birthday cards, and I guess Kwanzaa and Hanukkah cards are just around the corner.
If you prefer beer over eggnog, maybe sending branded Stella Artois holiday cards is the right choice for you (but you must be over 18 to create them). The best thing about Stella Artois application is that for each card sent, they will protect one tree from being chopped down.
Judging from Halloween, we can expect many more AR applications this coming Christmas. I'm willing to bet someone will create an application the puts a Santa Claus beard around your face, and I'll be here to cover it, when it happens! Oh right, Microsoft and Ubisoft have done just that last year, and Talking Dog Studios have it covered this year:
Many thanks to Development Memo For Ourselves for finding the link to the ARWishes app. Also check out Ori's coverage of 2008 holiday AR greetings.