In case anyone was curious what I did with my iPhone application, I did end up releasing it for jailbroken phones. It's called
ContactXfer and is available through Cydia. It's beta for sure, though I haven't received any complaints.
Looks like it's even getting a tiny bit of
attention, which is fun. The code is pretty crappy, but I've got tarballs up if you want to take a look. You can marvel at the insane steps I had to go through to contend with the removal of ABPerson serialization from the AddressBook framework (it's in the regular osx version, but not the iphoneos version). I guess they didn't want people serializing address book entries or something.