Regardless of wht you may think of Apple and it's OS, they do manage to get some things right. Their use of multicast DNS and its' widespread support points to the future. Sitting at a tbale at ApacheCon I watched while the apple users (far, far fewer than last year it has to be said) browsed to each others music stores and played them on their own machines. The abilities to make this happen aren't revolutionary, but the seamless nature with which it can be done was. If we want computers to become more of a "consumer" device and carry less of the aura of impregnability that they presently do for smany people this sort of ability will have to become common place.
While the feature is cool I do wonder about how easily it will translate to other OS's. Apple have showed some incredible tenacity in defending their protocols, effectively limiting the wider adoption of them as standards. The spectre of a repeat of the IM "wars" where the early players all had their own protocol and refused to interoperate with others should be enough to cause some concern. Truly open protocols are the bedrock of the internet and it's success. Whether code is also made available is largely irrelevant providing their is an agreed, publically open standard for people to follow.