Hmm …

… Language Log — Language as a self-regulating system. (Hat tip, Dave Lull.)

Greene points out the "semantic creep is how languages work", and provides a couple of examples, "decimate" (killing every tenth soldier > annihilate) and "literally" (factually > figuratively).  The descriptivists go with the flow, the prescriptivists lament the loss of the original meanings.

The real problem with things like this  is that they suggest sloppy thinking goes along with the casual usage.