Still true, but used to be far worse with monochrome displays. I work in a large Computer controlled Water plant and our displays are on 24/7/365 and definately burn our main screen into the Monitors. The remote workstations that are not manned around the clock use screen rotation and we have no problem there. You don't have to switch screens very often to be effective however and I would consider our situation to be worse case, and the screen burn-in has minimum effect anyway, due to the fact that we use the screen that burns in 99% of the time anyway.
edit: Hey, looks like I'm Platinum baby...woohoo