The n95 from nokia is not directly supported by mac osx. However - there are two additions that will help.
Nokia themselves provide an iSync plugin that will give you full syncing of iCal and Address Book. More info available from Nokia
Address Book pairing
This is not sync - but the ability to send SMS, and receive incoming call notifications via bluetooth. You'll need a plugin to Address Book - available from Nova Media. Note - outgoing SMS works fine, incoming call notification and ability to answer with SMS also work fine - but incoming SMS does not. This is apparently due to Nokia and the phone - it doesn't support this according to Nova Media.
3G over bluetooth
This does work - but the configuration scripts are not part of osx. You'll need to grab them from Taniwha