> there is no technical reason why the latest iPhone SDK cannot run on Snow Leopard.
How exactly you know that?! Maybe new SDKs (that are compiled to run on x86 for iOS Simulator) use ARC exclusively which doesn't work properly on Snow Leopard. It makes sense to do so now that ARC's been out for a couple years...
What application released two years ago isn't running on Mountain Lion today? The only one I could think of would be Xcode.
> there is no technical reason why the latest iPhone SDK cannot run on Snow Leopard[0].
Snow Leopard was released in 2009. Just because something can be hacked to run on an unsupported platform doesn't mean you won't encounter an issue. It's not just about dropping a platform as a target; it's also the fact that it won't be officially supported (meaning no guarantees or bug fixes), Apple's engineers won't be going out of their way to make sure the SDK and the simulator run, and they won't help you with technical support. If it does work, and there aren't any known issues (which I doubt), it's a happy accident that could break with any update.
My Quicksilver app hasn't changed since 2008. It's an old app but it still works being 5 years old. Maybe you're running poorly built apps and you should be complaining about shoddy developers instead of a shoddy operating system.
there is no technical reason why the latest iPhone SDK cannot run on Snow Leopard[0].
this is purely apple forcing users into the upgrade cycle and everything that comes with it - the App Store, code signing, etc.
[0] it has been backported and works. see: http://stackoverflow.com/questions/9613565/is-it-possible-to... amongst others. It is as easy as copying the library over.