It's been all over Aussie TV for days, as well. Today's news was starting to get creepily second-hand - the news coverage was all about the news coverage, rather than just the woman herself.
I do think (the cynic in me) that a big factor in the "WOW!" effect was her choice of song. The song was about having a dream, she herself represents that dream and the whole thing seems like a magic fairytale. But if she had sung the national anthem, for example, she still would have got a "Wow, what a wonderful voice!" reaction, but the teary response to her might be a bit subdued.
What I saw getting the response - not just the voice, but the juxtaposition of that voice, with those looks (or lack of) coupled with the choice of song being a heartfelt plea to never give up on your dream.
I don't know if she chose tat song form the heart because of the words, or because she liked the sound of it, or because she knew it would 'sell' or because she just knew it would suit her voice - but whatever the reason, I suspect that underneath it all, she has a good instinct for what works best for her. If thsat is the case, then that is one more 'star' factor she can use to her benefit.
I really hope she takes this further and becomes the entertainer I'm sure her mother knew she could be.
Marg
PS And I especially liked the way the bad-tempered smirk of derision was rapidly wiped from the face of Simon Cowell - when he heard she was unemployed and 47 (or however old) you could see him thinking, "OK, another loser!" until that first note - and then his eyebrows crept into his hairline. Then he began to smile. THAT was lovely!