Ask HN: Australian hackers working in the US?

I'm an Australian programmer curious about work in the US. I recently started working at a medium-size company (2k employees, at least 100 other programmers) doing C# web dev and Perl systems stuff. I have 2-3 years prior experience with Python + JS web dev, and a math(s) degree.

I like my job in Australia, but in the future, I want to spend some time living and working in the US — ideally in SF or NYC which I've visited and liked. It seems like I wouldn't have any trouble getting an E-3 visa, bypassing the H1-B lottery, if I could get a job offer.

Are there any Australians who have managed to do this? How did you find a job? I've seen a few positions advertised on HN that look appealing but they tend to require you to already have permission to work in the US. Is it worth applying anyway, since I wouldn't need a H1-B?

Is it realistic for me to ask a company to sponsor me at this point in my career? Reading HN gives me the impression that developers get better pay and more interesting work in SF, but I'm not sure if that's true for more junior developers. Would I be better off working in Australia until I have 5+ years experience under my belt?

Thanks in advance!