My order:
1. Buffon
2. Cech
3. Casillas
Other notables: Van De Sar, Reina, Lehman, Kahn (still very good), Friedel, Frey (should be the French # 1, if you ask me), Julio Caesar (best of the Brazilian lot, if you ask me)
Reina is doing well in a league where Latin keepers have been known to flop, and his range on crosses has improved since he joined pool; he holds more than he punches now. He also gets some time for Spain, and that says a lot.