I see that Jetstar have revised their logo, with the full name spelled out so that it now reads "Jetstarstar" ;-)
Jetstar Asia have dropped the word Asia from the logo, so they are all now indestinguishable, and I've added country flags to the standard logo.
JST - Jetstar (the original Australian company}
JSA - Jetstar Asia (Singapore)
PIC - Jetstar Pacific (Vietnam)
JJP - Jetstar Japan (started operations last week)
Jetstar Hong Kong is coming sometime soon, but I can't find an ICAO code yet.
Rod