Voice Mac 5.1 - Client for Google Voice. (Free): "Voice Mac is a client for Google Voice the features are described below. Short Message Service (SMS) Voicemail Calling people using your forwarding phones. Contact list with the options of Google Contacts or Address Book. Contact Filter. Growl for SMS and Voicemail. SMS History so you can go and view old SMS."
MacUpdate - Universal Binary - http://www.macupdate.com/macintel.php