Derived from the breaking down of the word awesome:
"Awe" as in, to be in awe.
"some" a little bit.
This, I believe, does not truly reflect the user's intention when using this this word. When awesome is used it is generally used to describe something really good, instead of being "a little bit" in awe.
Hence the alternative term...Heaps-awe.
This also runs wth the South Australian theme of "Heaps Good".