lucy24 - 2:00 am on Aug 2, 2013 (gmt 0)
It's covering its bets by allowing both options: either you're searching for the site itself, or you're searching for the text string "example.com". In the second case, the search engine would bring up other sites that name yours. Generally your sitename wouldn't occur very often on your own site-- especially not with trailing "dot com". (Look at the present page for comparison :))
But then you learn something else: of those sites that mention yours by name, you can see which ones the search engine considers most relevant and/or prestigious.