Known for his vulnerability research on older versions of Internet explorer, His main targets where Microsoft products, but he did find some flaws within other products as well. George has now publicly retired from the Vuln Dev scene.
Most recently found a remote denial of service exploit in Apple's Safari browser.
Apple's fanboys tried to kill him Children of the Corn style for finding a security weakness in their products!
http://www.milw0rm.com/author/207
http://www.guninski.com/