Apple have some details on their developer site about using the “Grand Central Dispatch” system. It is interesting to note they mention both Mac OS X and iPhone OS as using the less-threaded, more-asynchronous design approach. Multi-core iPhones are inevitable I guess.

Edit: Further juicy details – Apple extended C in 10.6 to provide language support for a “Block” object – equivalent to a “lambda” in other languages. I found the extension specification on the LLVM site here.