I have OS 10.6.6, iSync 3.1, Address Book 5.0.3 and a NOKIA 6500c Phone. I successfully installed the plugin for the Nokia (at least it seems like it, the phone is recognized).
I have like 6 contact in Address Book and like 150 on Phone. When I do the "first time" sync I chose "merge" phone and computer. When doing the sync, on the phone display a status bar appears and it says x/150 synchronized, as should be, and within a few seconds its done. But the contacts do not appear in Address Book. I've tried this a few times after resetting the syncing settings and everytime I do the first time sync, it appears to work, but nothing appears in Address Book.
Funny is: If I change the phone number of one of the existing 6 entries, that I have in my AddressBook on computer, on the phone, the change is synchronized to the computer. But no new entries are entered on the computer.