We have officially launched support for 2-Factor Auth for withdrawals! We utilize Google Authenticator, and allow you to set up your account to require an OTP before every withdrawal request.
That is awesome! Thanks!
and redeem private key (w/ button for scan QR code) to add funds.
Unfortunately, we have back-burnered this feature (again). Sorry about getting your hopes up before, but there just isn't a good option here implementation-wise.
Incidentally, piuk made it pretty easy to offer this where you don't need to add the private key to your own wallet, ... simply supply the destination address in an API call: