Well, personally I would not say an upset because Sri have beaten Aus before. Although, Aus missing Gilly, Heyden, Warny and "Mr Drinker" Symonds, has produced a pathetic batting lineup for which there is no replacement!
So, I am not sure what will the Aus will bring during worldcup, unless that is they bring all the oldies back, in which case, still their performance cannot be guarenteed.
I think that Aus deserved it because they need to come down to earth. After years of domination and high flying in cricket world and a good whipping by India in semi last T20 world cup, and WI this T20, I think this is the right outcome for them to realize there are other potential candidates for the position that they held with so less regard!
I like them though