I'm also not clear how the recipient supplies their info to the sender's bank. If I don't have an ING account, how can they verify that I'm me, and not someone else who's pretending to be me in order to intercept the transfer? As I recall, when I've done wire transfers, I've always been given the account info of the recipient for me to provide to my bank (but I haven't done this very frequently).
Edit: I just saw your other reply where you describe the ING app. I guess that works, but it's rather unfriendly. I'm always a little wary of high-security stuff (such as money transfers) that depend on email, too, but that's also an issue for Dwolla and probably a lot of the other payment startups.