You may be wondering what it means to see 'google.com' as referral traffic in your Google Analytics admin. When most people think of Google traffic, they think of Google Adsense or organic search results, but google offers other services like Google Sites that can count as referral traffic.
Google offers a whole slew of services outside if its search engines that are capable of referring traffic online, including, but not limited to Google Places, Google Sites, Google+, Google Docs (published pages) etc. Google's services are growing everyday, and I'm sure the list will expand.
A lot of the time you will see referrals from google.co.uk, google.ca, google.com.eg etc. This is the same scenario only; the Google services are in foreign countries.
Here's the official explanation on the topic: http://support.google.com/googleanalytics/bin/answer.py?hl=en&answer=55587