For the K/S Advent Calender 2011
From the prompt: Kirk/Spock have been bonded five years and have a child (can be adopted or their own). Cue family holidays and general happy domesticity.
So yes, Kirk and Spock have a baby and they celebrate their first Christmas as a family. They also adopt a sehlat for the baby to be friends with.
Here are a few pictures of the first Christmas together :)