Support for new Nokia phones is added at each iSync release. However the lag time can mean early adopters are left without a sync solution on Mac OS X.
Nokia site:
Get organized with iSync. If you've got a compatible Nokia phone and a Mac, iSync helps you synchronize your data. Take the hassle out of managing data across devices by downloading changes and updating your phone or Mac when required. And there's no need to download anything extra as iSync compatibility is included in many Nokia phones.
The plug-ins enable the sync of Calendar and Contacts in both directions.
More information is available from the Nokia website.