Thief 4 was announced way, way back, when Deus Ex: Human Revolution was in early production, and now CVG reports on a rumour found in the most current issue of OXM that development has now moved on to the generation of consoles. Hardly surprising given that Thief 4 probably did not enter full production until after Deus Ex: Human Revolution was completed last year.
Anyway, we eagerly await any information on Thief 4, especially given how good Human Revolution turned out.