Hi & welcome to MR.
I also bought a Sony with total ignorance about the restrictions (who would think about asking that). There are some sites that will sell you books.
I have now got myself a travels creditcard from my bank preloaded with US$ (you can also get one of those creditcards that are preloaded with AU$) and have increased the number of bookstores that now sell to me. Never mind that I have to 'bend' the rules a bit and Brisbane is now in the US
. I figure that is still more honest than having to rely on pirated copies of bestsellers I want to read.
But to answer your question: I contacted Sony to ask if they sell their reader in Australia soon and received a non-commital reply. So as long as they won't sell overseas they won't have much need to internationalise their bookstore.
But keep checking the forum - lots of bookstores mentioned and added to on a regular basis.
And enjoy your reader - despite the problems to get books you will soon love it.