Well, things might change as reported by Simon:
An iSync-dedicated plug-in for the P990i was released on my-symbian.com forum. It seems to be derived from an undisclosed version developed for the P1i, and is reported to work only with P990i loaded with the last firmware update. Several users have successfully used it.Do not hesitate to report your success or failure on our forum (here) with those unofficial Mac plug-in for SE UIQ3-based mobile phones.
http://my-symbian.com/forum/viewtopic.php?t=33135
Another plug-in should give m600i owner the possibility to sync their favorite mobile phone with their Mac... it did not work with mine, but one might need to further investigate...
