I don't have a perfect answer to this yet but since you don't have any, I'll take a stab at it.
Basically, I have my site setup on .com and .com.au - I have used the hreflang tag to identify a specific domain to be shown to Australian users. This means on Google.com searchers see .com and on Google.com.au they see .com.au but the content is essentially the same.
So far, the difference is that my sitelinks have not (yet) been indexed in Google.com.au even though they have in .com So it's not a perfect translation but the hreflang tag is new.
What we have also done is simply direct the site over.
You should also check out one of our best Australian SEO blogs on the topic.
