Doesn’t pass the smell test.
Most banks don’t have smartphone apps, so in order to do banking, you either use their website on your mobile browser, which is no less secure than a desktop PC, or you use text messaging, of which nowhere does a feature exist to withdraw money via text message that I know of.
With many banks requiring two-factor authentication and SSL (so no eavesdropping on wifi networks), I find it hard to believe that any fraud happens on the consumer end. Hacked websites with credit card lists seems like a far bigger threat to me.
A quick search of the Android Market reveals approximately 700 distinct "Bank", "Credit Union" and "FCU" (common acronym for Federal Credit Union) apps. Most of them are specific to a particular bank.