But on the upside, if they can make a safe and convenient "cash app" for phones, they will be able to automate some of the drudgery (and hence cost) associated with handling deposits, because they won't have to shift as much physical cash around.

The latter point might actually be the main business venture for a cell phone operator, at least initially. In Denmark alone (5 million people), it's estimated that firms and banks spend on the order of a billion € a year on handling petty cash. So there should be an R&D grant or two in that project. And a couple of hundred million Euro in licensing revenues if they can get people to switch to it wholesale.

And at least in the UK, deposits are perfectly safe, but plenty of people don't believe that they are safe...

OK, point. But I'd be careful about trying to play on that. Because the BoE and Chancellor might, eh, take exception to people starting bank runs for fun and profit.

- Jake

Friends come and go. Enemies accumulate.