Hi Ken!
We do not currently have a Campaign Automation Action or Nurture Step that allows you to send out SMS messages within the processes. I would suggest filling out a feature request for that here: http://support.clickdimensions.com/forums/356780-Feature-Requests.
As a workaround, you should be able to use an on-demand workflow to send your SMS through a Nurture or Campaign Automation: http://help.clickdimensions.com/sending-sms-messages-from-microsoft-crm-workflow/