Word from the University of Queensland
is that the scramjet tests were indeed successful; right up to the point where the scramjet melted, as designed. (And, it's not often you can say that
with a straight face.)
Interestingly the Australian team deny that ensuring combustion in a hypersonic scramjet is particularly difficult- apparently the air inlet compresses the air, and the air temperature is then high enough to support combustion without further ignition.
Personally, I am pretty skeptical as to whether this will ever be a practical form of transportation or a way of launching a vehicle straight into orbit (due to weight considerations). However, it might make a reasonable weapon, and the the military are indeed pushing for its development the hardest.
Basically, the thrust/weight ratio of a rocket is about 50. The thrust to weight ratio of a jet engine is about 5. The thrust to weight ratio of a scramjet is about 2. That means that a scramjet is heavy, and heavy is a very bad thing if you want to make orbit.