Just found Another survey showing that insider threats are very real and that it's actually getting easier for insiders to steal information. From the article: "Pilfering data has become endemic in our culture as 85% of people admit they know it's illegal to download corporate information from their employer but almost half couldn't stop themselves taking it with them..."
http://www.net-security.org/secworld.php?id=8534

The moral of the story is that if you care about things like your customer list, product information and business plans, take serious action to protect it! If you are unsure if it's safe or not, hire someone to do an audit and advise on how to address the issues which are found.