Slashdot now has links to reports that worms exploiting holes in Microsoft software recently shut down safety systems at a nuclear plant for five hours, and just yesterday shut down the signal systems for Maryland commuter rail.

There are two problems here. One, that these systems were exposed to the internet in the first place; it's not at all clear what could justify the risks. The other, that they're using software with such known, and notorious security problems -- which would make them vulnerable to insider attack even if they were properly isolated from the larger public net...