I'd like to extend the Contacts application in Diablo in order to show more vcard information like someone's physical (snail) address.

In a way, the Contacts app is extendable as new IM protocols generate new options and having a web URL adds a "Open Web address" button. But I don't know if there is a way to extend Contacts in order to add new fields.

I've already written some Python code to access the address field from a contact but I'd like to be able to set it using the Contacts app if possible.

Is the source code of that app open ?

My final goal would be to write a local version of the route downloader used by Maemo Mapper but that allow you to put a friend name as the source or destination and more stuff like alternate routes.