The one to attend is http://www.cac2005.com as it is attended by most affiliate programs and many US and global affiliates. September 11-12, and precedes the G2E (Global Gaming Expo). Since you are coming all the way from Aus, it would probably be intersesting for you to attend it, although predominantly land based operations exhibit there.
There will, more than likely, be other affiliate events happening around that time so it will probably be a trip that you can get a lot out of.
some sites to look at are:
http://www.gamingfloor.com/
http://www.osneymedia.co.uk/events.asp?etype=telecomgaming
http://www.ateonline.co.uk/default.asp?showid=21
See you there!