It was already leaked that Snow Leopard seeds are now API complete, but according to Kaiwai, many people misunderstood as to what this actually meant. "The first misreporting was that it means, "this is stable and all builds from here will be testing" which is 100% patently wrong," he writes. Obviously, API complete simply means that from here on out, both Apple itself and 3rd party developers can start making use of the new and changed APIs comfortably knowing that the APIs will no longer change. They're now a fixed target instead of a moving target, and that's very important for developers.
Kaiwai presented his overview of the Snow Leopard seed as a straightforward bullet list, and a few of those stood out to me. First of all, he did some small tests to validate backwards compatibility, and as it turns out, the few applications he ran had no problems running, such as Handbreak 0.9.3 to compress some videos, Office 2008, and Adium 1.3.4. Since Office 2008 is a pretty complex application, it's good to see it works without a hitch on this new major Mac OS X release.
Being a PowerMac G4 owner, I'm obviously quite interested in how Apple is going to treat stubborn PPC people like myself: will we still be able to run Snow Leopard? Will they remove support for PowerPC entirely? Or will the move to a 64bit kernel mean that they will no longer ship a 32bit kernel, meaning only the G4 gets cut?
The general idea is that yes, PowerPC support will be dropped, since the optimisations planned in Snow Leopard provide no benefit for PowerPC users. The move to full 64bit, for instance, will only slightly slow down 64bit PowerPC G5 machines; the number of general purpose registers between 32bit and 64bit PPC is the same, so 64bit PPC code will only suffer from having to deal with larger data items.
However, that was assuming Snow Leopard only included performance improvements. There are hints that Snow Leopard might also bring user-visible improvements, and I would be saddened to see PowerPC users not getting to use those. Understandable, from Apple's point of view, but still.
Kaiwai's overview talks a lot about PowerPC code, and what I hear doesn't make me very hopeful: "Within the Applications and System directory many of the services are now Intel only which include Finder.app, SystemUIServer.app," he writes, "However, there are still components that include ppc code; although the amount in megabytes is minute I question why they are still there - will we eventually see this stripped as the development goes further on?"
The article is quite detailed, so I suggest you take a look at it if you're interested in where Snow Leopard is going.