That's definitely a tough one.
I am a former QANTAS girl and I am exactly 164cm, just 1cm over the 163cm minimum height and it was a big issue. They measured us all in a great big long line and as I followed a couple of 5'10"+ girls I am sure I looked like the resident midget - lol. However, I did pass the height test, but the recruiter measuring me made a point of saying "oooh, only JUST!! You are very lucky", and then measured me again paying particular attention to if my feet (I guess to see if I was tip-toeing etc). A few candidates after me another girl who was also smaller in stature was measured. She was under the height requirement by 3cm and was turned away right there and then and told her "application would not go any further". I remember it distinctly as the young lady in question had travelled from the South Island of NZ for the interview; and to not make it past the height check must have been devestating (financially and emotionally).
I believe that Jetstar (going under QF rules and regs) would have same standards. However, I know Freedom Air in NZ doesn't have a specific height requirement - just a reach test (I think all airlines should have this! If you are tall enough to reach the Emergency Equipment in all areas - then you are tall anough to operate in my opinion).
A friend of mine is 156cm and worked for a smaller airline in Australia and then in NZ on Origin Pacific, so it may to shop around for airlines with smaller aircraft.
Alternatively, be completely upfront with Jetstar, write to the them stating your wife's height, that she is more than happy to do a reach test and formally operated on A320s and hopefully they will make an exception. Esp with her awesome wealth of experience!!
Good luck and let us know how it goes ... and welcome back Down Under
