I have done some calculations to see how much it would cost, if I got the cricket promotional fares from Jetstar, for a girlfriend and myself to fly SYD - SGN (hochiminh, VN) - SYD. It did not look that attractive.
The normal Starclass (or pseudo business) fare for SYD - SGN in February is $1,198.45 (inclusive of taxes & charges) and SGN - SYD $1,179.19. Total return fare for 1 pax is $2,377.64.
The promo fare Starclass for SYD - SGN is $604 (Australia's first innings in the first Ash test), plus the return leg SGN - SYD will just be normal fare of $1,179.19. Total return fare for 1 pax is $1,783.19 - admittedly this is $600 cheaper than normal fare, but is it worth it? If I really want to go to VN then the answer may be yes, but if I just want to pick up a bargain then the answer will be no.
Also, I noticed that when Jetstar first advertised its international routes, the Starclass one-way fare between SYD and SGN was just over $800, now it has gone up by $200.