Apple is running a seasonal screen saver on Macs situated in its retail stores which depicts a snowstorm – and it's available as a free download.
The screen saver – Snowfall – is a Quartz Composer-made set of visuals for the Mac, and it's available now for download. It features a range of snowflake images taken by Wilson Bentley.
The screen saver only works with Mac OS X 10.4 and must be placed in the /Library/Screen Savers/ folder on your Mac (or in the same /Library/Screen Savers folder in your Home folder). Its behaviours can then be modified within System Preferences.
The software is a 411kb download and is available now.