"By that I mean they can't find how these mobile devices are improving worker productivity, which computers have been doing quite ruthlessly for the last 70 years."<p>Actually, computers in general have failed to show up in these measures for a long time:<p><a href="http://en.wikipedia.org/wiki/Productivity_paradox" rel="nofollow">http://en.wikipedia.org/wiki/Productivity_paradox</a>