Then again Apple already had the libraries for native app development because they were developing apps themselves. They already had iTunes. And you know what? The same people that approve iTunes music submissions also approve App Store submissions. Most of the pieces were in place - they just had to put them together. 7 months doesn't seem too long for a version 1 app store.

Edit: And the question isn't really were they going to have an app store or not - they very well could have been thinking along those lines but reserving it only for software they themselves were going to create or with select partners - the question is whether they were going to open it up to general developers which I think they did not want to do.