I think what the # of iPhone apps represent is the (commercial) developer's community interest on the platform. That is their strength: Apple has found a workable formula where:

- The platform is interesting enough for 3rd party developers to create new products and sells on at an acceptable revenue.
- The customers likes the quantity and quality of apps enough at the suggested price points
- Apple gets a nice chunk of change from all this and maintains the system in exchange

IMHO, you can't just create an open platform and throw it out there and hope for the best to succeed. That is what we're seeing in step 4 out of 5.