Did Beyonce lip sync on the Oscars dance number last night with Hugh Jackman?

Yes, absolutely. It was clear from several angles that she was. It wasn't a time delay thing either, because at some points she was singing in time with the song and at other points she was not. Also, did you notice that several times when she started to "sing" that she turned away from the audience (by looking over her shoulder or turning around) so there was no obvious "lyrics starting before her mouth starts moving" moments.