Since my previous post about the contacts merger, I fixed a crash, made it handle better broken vcards, improved the partial matching and made the installer quit the address book when the plugin is installed, so no reboot is needed.
The new 0.1.3 merger is now available in Maemo extras-testing, just look for “Merge your duplicate contacts” in the application manager.
Suppose I could have some spare time to write some small applications relating to the N900 address book; what would you want me to work on? The application should be small and not require changes to the closed source components. Suggestions are welcome in the comments, but I cannot assure you anything
Update: I meant extras-testing of course, not extras