No Google Authenticator support though. No list of backup passwords either. So if I lose SMS access on my phone, but still have my phone, I still can't get into an account from a new device.
And I imagine Twitter thought of the lost phone/sim card problem, is there really no set of preshared backup keys?
You get app specific passwords, but they're only good for an hour. By then, your app should have a token that is good indefinitely (and you can revoke from their apps list).
Based on the "..much of the server-side engineering work required to ship this feature has cleared the way for us to deliver more account security enhancements in the future.." I'd expect support for an OTP client soon.