Just released in a letter to College Board consultants: Beginning next year (on 2011 exams), the multiple choice score will not include the "guessing penalty." The multiple choice raw score will be the total number of correct answers, period. Expect a formal announcement to all AP teachers in August; the course descriptions on AP central supposedly now reflect this change.
What does this change mean for you? Well, it should mean almost nothing... students should always guess on multiple choice questions that they read. However, it now becomes critical that students make random guesses if they are running out of time at the end. This is certainly a substantive scoring change, but I believe that its effects will be way overblown on message boards and in conversations. It's not a big deal.