I don't know how accurate it is but WikiAnswers provides this:
http://wiki.answers.com/Q/How_many_quarterbacks_have_won_a_superbowl_with_two_different_teams
No quarterback ever started for two different Super Bowl winners, BUT Craig Morton is the only quarterback in NFL history to start the Super Bowl for two different teams (Dallas in 1970 and Denver in 1977).
Kurt Warner, QB- Arizona will be only the second quarterback to start the Super Bowl for two different teams when he takes the snap in Tampa on February 1,2009.
These two quarterbacks played for two different teams in the Super Bowl:
Earl Morrall, QB - Baltimore (III, V), Miami (VII, VIII)
Jeff Rutledge, QB - New York Giants (XXI), Washington (XXVI)
Also the following were on the roster but did not play 1 or 2 of the games.
Matt Cavanaugh, QB - San Francisco (XIX*), New York Giants (XXV*)
Jim McMahon, QB - Chicago (XX), Green Bay (XXXI*)
One quarterback left out of the two different teams in two super bowl that only played in one of the two games is Neil O'Donnell in Super Bowls xxx, and xxxiv as a member of the Steelers and Titans respectfully.