I can't respond to Dr. Rousseau directly for list subscription reasons, so sorry about screwing up the thread a bit.
I would be impressed if "gpg2 --card-status" didn't just hang. I understand that GPG has its own card server program and wants exclusive access to the Yubikey. GPG2 works on RARE occasion and I can't figure out the why's and when's even though I've tried.
But from reading various looks at Apple's current smartcard service, it seems like it doesn't get a lot of love. I assume that Apple hasn't really dedicated a significant number of engineers to this. And from reading your blog, Dr. Rousseau, it doesn't feel like you believe in Apple's roadmap, at least from the parts that are visible.