SMS Marketing?

I have had several conversations with my wife about whether companies should be more interested in creating a "app" or using SMS.  I am a firm believer in the power of text or SMS.  Mashable just published an article - Why SMS Marketing Still Makes Sense for Small Business, and it was really interesting.  We carry our phones with us everywhere, and we feel completely lost when it is not with us.  It is intimate and because of that reason an incoming SMS message usually means something to us.  We want to read it and and more than likely reply immediately.  How many other forms of communication create that same sense of intimacy or urgency?