Best Mobile development platforms... (where you the developer can make money)
1. Windows Mobile
iPhone: One No from Apple and you're out of business. No viable ecosystem (IMO).
Android: Too much fragmentation and missing features from the core OS.
None of the code from one platform is supported on the other, you have to port or re-write huge chunks, especially where the user interface is important.
Seriously expensive to develop on all 5 platforms. Only one thing supports all platforms and that's HTML.
IMO the trend is going to be Web services on Mobile. SImply too expensive to support any other approach.