I'm flying over as well. Provided you pack the bike in "an approved manner" you should be OK. That said Jetstar managed to wear two holes in a brand new bike bag and wear down the headstem in the process by dragging the bag. Virgin were fine and this will be my first attempt with Qantas (and SkyWest for that matter). I recommend getting spacers for the forks and for the calipers if you have disc brakes - bike shops will have them leftover from when they assemble their bikes (got mine from Clarence street for nicks)
If you can afford it I recommend the groundeffect tardis bag http://www.groundeffect.co.nz/product_d ... tegory=BAG
. I can't rave enough about their gear.