Faces problems; intrinsic to iPhoto '11 or due to library upgrade from '09?
Examples of Faces problems include:
(1) Photos in my Unnamed Faces smart folder (Face-is-unnamed) that show no unnamed faces
(2) Mis-matches between Info frame list of faces in the photo and the face frames visible in the photo
(3) Fewer photos appearing for face confirmation than stated; usually one less. Sometimes I am told there is one unconfirmed face, and none appear at all.
(4) iPhoto offering faces as possible matches that look (at least to me) nothing like the face in question, (although they may be in the same photo), but failing to offer identical or near-identical poses of it.
2.93 GHz i7 iMac, Mac OS X (10.6.5), iPhoto 9.1 ("iPhoto '11")