Mathworks released MATLAB 2013b on September 6, 2013. See http://www.mathworks.com/products/new_products/latest_features.html?s_cid=0309_webg_9a_nn_278986 for information on system requirements and product enhancements.
2013b is a free upgrade for customers who have an active MATLAB subscription through the Software Store. We placed a free download for 2013b in the Software Store accounts of eligible customers.