Yesterday we released a PAM package into official, along with a rebuilt shadow package that has PAM support.
PAM is quite interesting (read: touchy and error-prone) to configure, so our second try is out today. When you --sysupgrade you may see some file conflicts between the pam and shadow packages. It is safe to --force these.
Thanks for your patience. Hopefully this is the last hiccup you see in our transition to PAM.