John Siracusa does an awesome job writing his review of mac OS X Snow Leopard for As Technica: Mac OS X 10.6 Snow Leopard: the Ars Technica review - Ars Technica.
Grand Central Dispatch is far and away the coolest technology that I've seen created in a long time for super-simple concurrent programming that fits your existing programming style/model.
If they were handing out Oscars for programming, the developers of GCD and the "blocks" extension to the language would get one. Heck, if they were handing out Nobel Prizes for programming, this would get one!
Makes me happy I'm an AAPL shareholder.