It seems to imply that even though there's a correlation between the pointy-haired boss leaving Dilbert's cubicle and receiving an anonymous email about the worst boss in the world, there's no causation.
THAT IS WRONG!
Clearly there's causation: PHB leaves Dilbert's cubicle, which causes Wally to send the anonymous email. PHB's implication that he thinks Dilbert sends the email is wrong, but that doesn't mean that the correlation he noticed isn't in this case created by a causal link between leaving Dilbert's cubicle and getting the email.
I think Edward Tufte once said that the statement "correlation is not causation" was incomplete; at least it should read "correlation is not causation, but it sure hints at some relationship that must be investigated further." Or words to that effect.
