Available for download is Send SMS 2.3, a new version of the Mac OS X Dashboard Widget to easily send an SMS.
We improved two important features:
Regarding the Group SMS feature, the widget gives more feedback about which mobile numbers in the group were actually not sent (because of mistakes in the mobile numbers). Also, we [...]

Version 2.3 of the SMS Mac Address Book plug-in is available.

We improved the Group SMS feature of the plug-in:
The SMS Mac Address Book plug-in now gives you more feedback
about which mobile numbers in the group were actually not sent
(because of mistakes in the mobile numbers). Also, SMS Mac will always
immediately submit the Group SMS to [...]