Having built the same kind of company from the ground up, I have good reason to suspect that most of Dwolla's transaction volume does not come from mobile payments, if the $350 million / year number is accurate in the first place. Some revenue comes from Bitcoin transactions, which the article doesn't mention, creating the false impression that Dwolla is already a mobile payments juggernaut. It isn't.
Dwolla does not integrate with any point of sale systems to the best of my knowledge, which means that the title of this article is basically fantasy.
Dwolla is also breaking California law by operating in a manner that allows California users to use the service without a money transmission license. (Having an investor that processes transactions for banks does not make Dwolla exempt. Anyone who doubts this should read the list of exemptions: http://www.leginfo.ca.gov/cgi-bin/displaycode?section=fin.... If Dwolla were considered a bank it wouldn't need a money transmission license in Iowa, which it has.)
I'm not a fan of that law, so as of yesterday I've sued the State of California over it.