Quick thoughts:
2 different languages sharing a piece of data ? XML sounds like a good plan. If it is heavy handed, may be JSON could work for you.
I am aware you mentioned both apps are working on the same machine (at the moment) but what happens if you move mobile app to a device? What happens if your mobile app:
- opens a socket
- reads XML for the data object from it
- closes the socket
- does its magic with the object?
Would it work for you ?
UPDATE
Check this out please: Where does the iPhone Simulator store its data?
However keep in mind that, as far as I know, this location may change from version to version.
It does not matter if you read it from a file or a socket, don't you have to change the mobile code? And sockets and files are just streams in *nix lingo, aren't they ? :]