In a survey conducted by Cyber-Ark published on November 23rd 2009, they found that 85 Percent of Workers Know It's Illegal to Steal Corporate Data, yet 41% have already taken it to a new employer.

Some other interesting stats from the survey:

• 60 percent admitted stealing sensitive information
• 52% say they would steal the information "just in case" they lost their job
• 28% would use the information to negotiate a new job

Bottom line - data is valuable, insiders have access, and with the right triggers, motivations, etc this can lead to nefarious behavior.  For more information on what it takes to make a malicious insider check out the following this white paper:  The Anatomy of an Insider: Bad Guys Don't Always Wear Black

Various papers, Webcasts, podcasts and related material on insider threats.