From my understanding this is a form of permission-based text messaging where companies, churches, organizations, etc can send coupons, specials, announcements, and other types of messages to the cell phones of selected groups or members.  It is considered permission based and not spam because the recipitents must opt in.  and  then also have the option of opting out.  The way they would opt in would be to text a keyword(s) that you give them into a shortcode, which is like a 5 digit phone number.  The incentive for them to text the keyword to the shortcode, from their cellphone would be maybe a chance to win a prize, or maybe a coupon.  But once they do you have their cell number, with permission, and then you can add them to groups or lists that you can send up to 160 character messages to. 

Ex:  Joe owns a pizza parlor on Maple st.  He purchases a plan from a shortcode agent and aquires his keyword(s).  Joe places a sign on his door and everywhere he advertises that reads:  Text Joe's (his keyword)  to 11223 (his shortcode)  for a free slice of pizza.  When the customer texts Joe's to 11223 they find the coupon Joe has made in his back office.  And Joe has their cell number and not just one because over 200 people responded.  This information is stored in Joe's back office.  Now it's been a couple of weeks and business is a bit slow so Joe decides to run a special offering a free drink w/all lunch purchases that day.  Joe goes to his back office and makes up the offer, selects the recipitants, and sets the calendar so that the coupons will go to all 200 customers at 11:00am that day, or maybe just half of them.  By lunch time Joes place is packed.

Has anyone heard of this type of marketing or are you currently using it?  if so with what type of success?

Thanks