I had to mask samba-3.6.23-r1 (which became stable a short while ago) in order to be able to update world again without issues. samba-3.6.32-r1 needs unstable versions of tevent and talloc, and it also lead to virtual/pam-0-r1 beeing pulled in, which would have lead to a whole lot of other packages being merged. See <http://forums.gentoo.org/viewtopic-p-7572718.html> for the corresponding forum thread.
I forgot to mention. I'm running amd64 (i.e. not ~amd64).
samba-3.6.23-r1 is not stable on any architecture at this time.
I double checked - you are correct. I had old entrys in my package.keywords file. Sorry for the noise.