Since we found it, SMS Mac has stirred conflict between price and convenience for us here at TUAW, but I nevertheless felt it pertinent to blog the latest v2.1. Besides the $10/yearly price and $5/50 SMS messages, quit a bit has changed from that original version. It now includes both a Dashboard and Yahoo! Widget, the ability to send SMSes to Address Book Groups, better features for delivery report handling and more.
If money were no object, I would call SMS Mac one of the most functional and convenient desktop SMS utilities I've ever seen. Unfortunately, its high price and yearly subscription model have scared this blogger off to find a more reasonable alternative.