I believe Jetstar could have paid a fine to send their planes into the sky. I've looked it up before, but not sure at the moment - what is the fine for breaching the 11pm curfew? Then again, you'd need everything in place (ground staff, ATC, fuel, etc) which may not be easy to get.
(I also note that Qantas snuck several planes into SYD after the curfew, although I presume a dispensation was given to them as can happen when extraordinary events occur).
Weather delays are not really the issue of an operating airline. Sometimes you'll find someone nice who'll help you out, but normally you're on your own.
Reading some of the comments posted on various news sites made me cringe. Yeah, buy a Jetstar ticket, expect that they'll hold your hand when something goes bad. TRAVEL INSURANCE people, or just self insure and cop the problems when they arise.
Jetstar would have had some issues this morning to get planes into their right locations, although I noted they cancelled several flights last night, so maybe the planes were already in their right locations!
Once again though, this proves a few things.
1. Qantas (and to an extent Virgin Blue) have a huge enough fleet and frequent timetable to be able to recover from weather and similar issues.
2. Low Cost carriers are a risky proposition at times, but remember they're cheap. Just don't forget they won't hold your hand when things go wrong!
3. Travel insurance for domestic flights does have it's benefits...