Why not use OpenID instead of/as well as Bitcard?

Firstly, thank you for providing such a great (and reliable service).

You recently added Bitcard support for user accounts, whilst Bitcard is a good Single Sign On service OpenID is, in my humble opinion, better, more useful and widely used than Bitcard.

So thanks once again for a great service, and hope you find some time to implement OpenID as an alternative log in method for user accounts.