I came across this:

Enterprise users are "actively and intentionally" evading IT security controls and ignoring acceptable use policies, according to Palo Alto Networks' first annual "Application Usage and Risk Report."
Quite frightening really?

The recent survey results from Palo Alto, a firewall vendor, are based on traffic from 350,000 users in 20 organisations that span the financial services, manufacturing, healthcare, state/local government
Details are here:

http://www.techworld.com/security/ne...m?newsID=12102

OK, I realise that is quite a small sample, and I don't know how representative or unbiased it is, but it does make you wonder?