AAMCAS said:Changes to the MCAT Exam
The Writing Sample section will be removed from the current MCAT in 2013. If you plan to take the MCAT in 2013 or 2014, the current exam will be modified and the Writing Sample section will no longer be part of the exam. In its place, a voluntary, unscored trial section will be added starting in January 2013. For more information please visit MCAT® Exam Dates and Registration FAQ.
It will still be the same length of time FYI, so they're probably adding more questions to each section for those who don't do the unscored trial section.