I'm not sure whether your question is whether the gratuity is included, as it was in previous years. If so, the answer is NO. You are responsible for all gratuities in 2008.
If the question is about the mechanics of how the gratuity is paid, it will depend on how many of you eat together at a particular meal. Because you are in separate rooms, you will have separate checks.
If there are six or more in your party at a meal (no matter how many checks you have), each check will have an automatic 18% gratuity billed. You can pay it cash, credit card, or by billing it to your room. The gratuity will be added whether the meal is a regular meal or a buffet.
If fewer than six dine together, when you get your check, you will get a statement that shows you the calculations for tips of 18% and 20%. Nothing will automatically be added; the amount you tip is up to you...obviously with 18-20% being the preferred amounts.