Well I managed to get on the trial!
Looks like you need to be travelling First Class, WP or CL. See
http://www.qantas.com.au/fflyer/dyn/.../oct/smartGate for the full details.
I think QF FF membership is needed at least as that is probably used to cross reference you back to a phone number and address for their survey/stat records.
Worth a try to ask if you want to get on the trial, but unless you're a WP, CL or travelling on F don't expect to get onto it easily I think...
Can't wait to try it out!
Does anyone know when the trial is due to end (if at all?)