Welcome to the boards! Australia is a very competative market -- consider:

*Travel and Leasure (or one of the big travel magazines) named Sydney as the best international city. (It could be a post on one of these boards.)
*Australia's hosting the 2000 Summer Olympics.
*United, Ansett, Quantas and Air NewZ already serve the market, as well as several other carriers (I think British and Japan.) So the market's tight.

SO Australia's a hot travel destination. That could be why its tough for other carriers like Delta to get in.

FYI: if you want to do Australia on an award ticket PLAN EARLY. I started my planning at least 9 months in advance because award seats dry up fast.