Is there a “Tipping Point” for mobile

Eric Schmidt recently spoke about the “Tipping Point” for mobile at a Telecomm roundtable in Davos.  What has actually “Tipped” in mobile? For argument sake, lets define “Tipping Point” as the point where adoption becomes main stream.  For mobile, “Tipping Point” would then depend on the underlying technolgies you are talking about such as Voice, SMS, J2ME, [...]