A long muzzle is prefered and the AKC breed standard reads;
Muzzle-- long, straight and fine, with slight chiseling under the eyes. Strong without lippiness. The chin definite enough to preclude snipiness. Major fault: lack of chin. Teeth-- white, strong and with a scissors bite. Major fault: undershot, overshot, wry mouth.
I had a cafe male Standard a few months back that had a shorter muzzle. Eli has a long pretty muzzle and I have to admit a dog with a long fine muzzle just say's Poodle. The shorter muzzle takes away from the distinct head appearance of a Poodle. However, some Poodles varry in muzzle length.