I wrote a small utility which is able to export iPhone OS 2.2.1 contacts into KDE-4′s Kontact application. If anyone is interested feel free to write a comment, I would write a public version then. It is tested in Ubuntu Jaunty. If you want and/or are experienced you can grab this preview. iphexport-0.1.tgz

update
useful links for this topic:
a script which writes into the iPhone Address Book
Japanese Wiki Entry about the SQL Data Structures of the Database (contains also other Databases!), translated into english via Google