This story is just incredible:
http://www.scmagazine.com/uk/news/article/539631/russian-stock-exchange-attacked-virus/
As more and more systems become connected to the Internet, problems such as this are bound to become more common unless steps are taken to prevent the propogation of viruses. I would hope that this machine was in violation of various security policies by being connected directly to the Internet and the exchange's network. Sadly most network policies currently rely on people to enforce them as there isn't a nice way to determine which networks a computer is attached to.
I also can't help but wonder if this was something that snuck past the virus scanner, or if the machine wasn't running a virus scanner.