From TV Guide:
"When we were breaking the story about the third Winchester brother, we knew the fans would scream that we had jumped the shark. Of course, adding a new sibling or relative to an established series is a classic and cherished shark jump, Cousin Oliver being the patron saint of the practice. (And sure enough, Sam and Dean are eating at 'Cousin Oliver's Diner' in the episode). Anyway, it became clear that we should beat the fans to the punch and title the episode, 'Jump the Shark.' Though rejected titles included: 'When Leo Joined Growing Pains,' or 'The Raven Symone Episode.'
"For fans who are worried that we are truly jumping the shark... watch the episode, decide for yourself. Personally, I don't think we're gassing up the motorcycle quite yet, but you tell me. And stay tuned for next season, when the boys take trips to London and Hawaii (haunted Tiki dolls!) and Sam and Ruby get married. And Ted McGinley joins the cast as the thoughtful (but hot!) college professor."
I love you, Eric Kripke. I'm sorry I made ohnokripkedidnt dedicated against your evilness. It should have been in praise of your awesome. (But meathooks! MEATHOOKS! WTF.)
But goddamn you, DEAN grows up to be a college professor.
Now give me a Boy Named Sue on the motorcycle (as played by Ben Browder) and I will send my housecat army to defend you over the wailing and gnashing of fandom at large.
As for this one: For fans who are worried that we are truly jumping the shark... watch the episode, decide for yourself. - I am assuming it's another Ben situation where the 3rd brother is revealed to not be related to them at all or the guy will be horribly killed. Maybe both!