True that the Apple TV thing was not programamable till recently but I gotta say there's alot wrong with the AppleTV - it seems to be pretty blah and nothing and found no real definitive identity - a wasted opportunity on Apple's part.
It was with the launch of the iPhone 3G when they came out with the SDK + App Store and it was a really well executed coup.
Do you know how you got software on your phone before the iPhone? Getjar or side-loading (with a proprietary cable almost no one had with apps that would sometimes hard break your phone).
a) Sensible means of payment, no need to setup credit card processing, do deals with carriers etc for developers. Oh and no carrier lockdown on installing applications.
b) Macs going x86 based so you could develop for Windows / Linux and Apple all on the one box.
Basically Apple managed to make it possible for small dev shops to work on the iPhone without spending huge amounts of cash AND get money from consumers.
They may have had the app store model planned out from the start for the next version of the iPhone, but didn't want to talk about it when releasing the first version because that would highlight the shortcomings of the existing product and cut into sales. But you still have to have an answer to the question of how you make software for the new product, so they say build web apps.
Rather than saying, "we will have an sdk too, sometime", they played it off as intentional, and continued working on it silently. There is just no way they built it all in the single year from the release of the iphone.
The rest, all the infrastructure needed to have a working app store would be a much more substantial project. It is this part that would be difficult to build in a single year, and would have had to be in the pipeline when Jobs made his statement.