On re-usage of third-party software

To say from the beginning: if there are things that I can reuse - great. However, I don't like to just port an existing application to the iPhone. By doing so I would get an old existing application running on the iPhone - not an iPhone application with its unique user experience. This is not my goal.

Similarly, I would be happy to re-use existing (open source) frameworks, however it may appear to be impractical: Cocoa APIs are quite different compared to (GNU, Linux or other) APIs commonly used in open source projects. Possibly it will take less time to e.g. rewrite the map rendering part than to port e.g. Mapnik to Cocoa and OpenGL ES. Though, we will see.