The 738NG aircraft are the ones with the sky interior,as far as I am aware QF doesn't have any of these on domestic routes yet,they have taken delivery of two 737 800's recently (VH-VZL and VZM) but these are not NG aircraft,they do have avod however.QF domestic won't be getting any NG aircraft until later this year (At least that is my understanding,if anyone has other information I'm happy to be corrected).
Cheers
N'oz
Edited to add: Just checked with a friend who is very knowledgeable on these things and he reckons the two recently delivered 738's can technically be classed
as NG's even though they don't have the sky interior,however you would need to be flying on either VH-VZL or VZM to be on a Next Generation 737,QF has
34 NG's on order to be delivered between now and 2013.
Hope this helps.