I didn't say don't worry about it. I've been following this worm on technological sites to the best of my ability (code is not my speciality) and this one is not your average bug. For one thing, it is designed to attack industrial control systems. For another, it appears to have been designed by a sophisticated team over a considerable period of time. This wasn't some guy in a basement.

Wikipedia has gathered a number of sources into one article, which is useful.

The Microsoft patch that addresses vulnerability to USB data sticks was released about the middle of August, and would have been installed in a routine Windows Update operation.