[mighty]

I think there's a lot Apple needs to do to improve the IA of the App Store, and they need to make the iTunes store accessible from standard web browsers rather than just the iTunes software. But there's nothing preventing iPhone app developers from creating websites for their apps, and there are a variety of sites that review apps. That you cannot buy an iPhone app outside of the App Store does nothing to prevent developers from gaining visibility outside of it. There is nothing preventing anyone from Googling for iPhone apps (just as you can Google for non-iPhone apps), than the developers themselves.

As for the differences in sales curves, that's actually reflective of how much easier it is to find and purchase new apps on the App Store (as well as the increased competition -> price reduction that their aggregation provides), as opposed to having hundreds or thousands of different purchase sites with their own method for payment processing. Also note that most iPhone apps tend to be for entertainment, for which an early sales spike and sudden drop-off is the norm regardless of platform...or medium.