A short guide to the Life Day event introduced with Patch 2.5.1 on Dec 17 2013. There is also a guide to the Gree event available here.
Life Day event will be coming to SWTOR from Dec 17 until Jan 1. Rewards include Sleigh and Cyan Sphere mounts. The Gree event will also be returning at the same time. Updated with more info on the Life day event released on Dec 16.