iSync compatible cellphones
From Mac Guides
iSync is an Application included in Mac OS X for syncing your contacts, calendar and to do list entries with your mobile phone. Generally most Sony Ericsson, Nokia and Motorola phones are supported, though the newest models may not be. Apple Maintains several lists of supported cell phones which depend on which version of the Mac OS X you are using. See the following links for more information.
Some PDA's are also supported and support is extendable to include other PDA's and Windows Mobile devices with the Missing Sync.
These links are all for iSync 2.4/3.0.
This link is for iSync 1.5