Don't know how much of this is simple speculation but Ken Davidoff over at Newsday has the following towards the end of his article about the Rocket:

While Clemens likely won't be a Yankee next year, Andy Pettitte almost certainly will. Pettitte, one of the most honorable players in the game, intends to exercise his $16-million player option for 2008 even though he surely could get a long-term deal in the free-agent market.