Not necessarily. BBVA has already this with Dwolla's real-time payment tech, FiSync. (Limited, I know, but it's the only cool proof of concept like it out in the wild)

Also, there's been a lot of work done through the Fed's remittance coalition on a supradirectory for destinations. Adding authentication capabilities would be the next logical step and they've already committed to using open standards (lots of ISO stuff to compete with though). Combined with whisperings of big bank projects and JP Morgan's CEO very vocal hatred for screen scraping, Oauth could be a powerful and quick-to-market alternative.