Previous reference to people playing people, in case you need to get up to speed are here and here.
In the biggest people playing people upset of all time, Cate Blanchett won neither Best Actress for playing Queen Elizabeth or Best Supporting Actress for Playing Bob Dylan. However, those playing the living were not shut out. Marion Cotillard won Best Actress for La Vie enRose.
The people playing people rule did rear its head in one other category. The makeup team from La Vie en Rose won for apparently making the quite striking Cotillard look like the bizarre Judith Piaf. Fine, but technically speaking, I can't see how that is more impressive than making Eddie Murphy look like an old Asian guy.