I am scared to post anything that even mentions a potential flaw in and Apple (Apple.com) but I feel that this is newsworthy enough to wade into the waters filled with the fanboy sharks.
Today Apple released patches for 18 vulnerabilities in its OSX Leopard OS. The fixes patched up holes in many different parts of the OS from ColorSync and Dock to the kernel and MobileMe. The most notable problem being the flaw with the PNG graphic formats enabling a hacker to compromise the Macintosh by simply getting an unsuspecting user to visit a website. The moral of this story being that every OS has its own flaws despite what people insist.