They are coming out! And the Student Doctor Network — a fantastic resource BTW — has collected the 2008 secondary essay questions for many medical schools. Rely on the wording you receive from the schools to be on the safe side, but for an advance peak, check out this thread.
A few tips for the secondary essays:
1) Make sure you answer the specific question.
2) Have the essays provide new information about you. They should complement the AMCAS application and any other info the school already has.
3) Do not just repeat the AMCAS essay.
4) The secondaries are about fit. Show them how much you belong at their med school by first researching the school and learning environment and then using your life’s experiences to show you are a natural for that program.
For more information, please see "Completing the Jigsaw Puzzle: Writing Secondary Essays."