Maria Shriver ... WINS 60th Birthday Bash Contest ... Serenaded by Stevie Wonder

Maria Shriver didn't have a highly publicized 60th birthday party Friday night, but there's no denying ... it was the best party in town.

The guest list was impossible to beat ... Oprah, Tom Hanks and Stevie Wonder just for starters. It was as classy as it gets at the Montage hotel in Bev Hills. Patrick and her other kids were there. No sign of Arnold as far as we can see.

Oh, if that's not enough, check out Maria dancing with Sean Hayes as Stevie Wonder belts out "Signed, Sealed Delivered."