Google Sites now provides a simple way to track site usage, by integrating with Google Analytics.

Editions impacted:
Standard, Premier, Education and Team Editions

Languages impacted:
US English

How to access what's new:
Sign in to Google Sites, open a site, and click 'Site Settings'. Navigate to the settings page for 'Other stuff', check the box for 'Statistics', paste your Google Analytics account ID in the box, and click 'Save changes'. (You'll need to sign in to your Google Analytics account to get your account ID.)

For more information:
http://sites.google.com/support/bin/answer.py?answer=92369