White snow agains the black ice ...

Great, I updated the document to reflect this.Thanks for informing me !

From what I read of the technical documents it is currently not possible, but it should be feasible in the future. (I can't really find pages that contain all the information, but here are some links.)

Each item stored in your keychain is individually encrypted with its own unique key. Furthermore, these individual keys are themselves encrypted with a master key, which is in turn encrypted with a key derived from your passphrase.

The thing they should do is make the master key also accessible using the certificate from your smartcard. But it looks like it's not implemented yet...