It seems as though Apple is putting a tremendous amount of extra attention towards security these days. For instance, Apple is (according to CNET) inviting known security experts from all over, such as Charlie Miller and Dino Dai Zovi, to evaluate the current developer preview of OS X Lion. This move is quite unprecedented for Apple, as it is the first time they have done this with one of their OS releases.
Giving free access to security experts is an excellent move for Apple, especially as Apple continually gains market share and becomes a more and more significant target for hackers and malicious developers.