Smart Card Authentication in Mixed Environments?

Rednerd asks: "I've been looking into Smart Cards as a good alternative to password authentication but other than the ISO 7816 standard there doesn't seem to be a lot of standards that govern the use of these devices. It seems pretty clear that if I was working in an all Sun, or Microsoft environment implementing a network wide Smart Card solution would be simple, but there doesn't seem to be a lot of heterogeneous Smart Card support out there. I was wondering what kind of experience slashdot readers have had with Smart Cards in mixed environments? What cards and card readers seem to work the best? How have remote users dealt with the use of Smart Cards?"