Here are two posts from Google Blog.

http://googleblog.blogspot.com/2006/12/tis-almost-season.html

... and after 10 days:

http://googleblog.blogspot.com/2006/12/where-on-earth-is-santa.html

Maybe the were less downloads than expected?
Or maybe it's a reminder for them who have look this KMZ only one time.