I've made some progress in my work with the iPhone SDK...
I've written a simple version of the My Collection app which reads data from the existing database I use for the Android version. I'd like to finish up the read functionality and implement adding and editing of items.
My hope is to get a working version and get the learnings I need to build the app on the platform.
The iPhone lets me do things Android doesn't from a user-interface perspective so I'm planning on using the databse from the Android version but the rest of the UI will be unique and totally "Apple".
I actually had an idea where I would allow the user to define their own types and they would create "Search" pages that would show items for their types (I would seed the app with some default search pages).
I can't yet figure out how I'll work in the needed code to perform the Amazon lookups, but that is only a minor hindrance in the grand scheme of things. If I can get the application to have stable CRUD support with a tweaked out UI, the other things should be simple.
Google also ported the zXing API (the barcode scanning engine I use) to the iPhone so that will be the same too.
I'm actually excited about that. I get to use SQLite on Android and iPhone and now zXing is supported on Android and iPhone.
It's a shame that all 7,000 lines of Java code I've put into the Android version are completely useless on the iPhone...