Back when the US government started charging for the ESTA authorisation needed by most Australians visiting the USA, some Lifehacker readers reported that this meant you no longer needed to fill out visa waiver paperwork before entering the country. That now seems to have become a reality for everyone, but the electronic checking process is more thorough than ever.
For years, anyone flying under the visa waiver scheme has had to fill out the "green form" on entry, but this requirement seems to have disappeared now that pre-authorisation is needed for everyone. Based on my observations of the queue at Los Angeles Airport over the weekend, "no form" seems to be the universal approach: there wasn't a single one of the old green IW-94 forms in sight across flights from multiple airlines. That means that you only need to fill out the blue customs declaration (and only one of those is needed for families).
One detail that's being checked more thoroughly, it seems, is the address of your final destination (which generally gets entered when you book tickets or on check-in). In the past, a hotel name has been sufficient, but the system now requires a street address for the hotel as well, so make sure you've got those details with you at the airport.
As we've noted before, applying online for an ESTA is essential if you're travelling to the US; failing to get one means you're very unlikely to be allowed to even board your plane. When I checked in for my flight over the weekend, the check-in agent said there were still people regularly showing up without an ESTA; currently, they're advised to go to a public Internet access point at the airport and try applying online. In most cases authorisation is instantaneous, but if yours isn't then your ticket will be as good as useless, so get it sorted well in advance to save panic.