Kindle aside, there aren't so many choices for local ebook purchasers. Dymocks has just expanded its range of titles, adding 3,000 books in DNL format and also embracing ePub.
Chances are you haven't heard of DNL, which is an Australian-developed format designed to closely replicate the physical book experience. The ePub standard has been more broadly adopted, but Dymocks is being coy about how many titles in that format it sells.
As Nick points out over at Gizmodo, this isn't necessarily a major advance: the format is DRM-locked and Dymocks' preferred e-book reader is massively overpriced. On the other hand, letting Apple totally control the space (assuming it eventually gets around to offering iBooks after eventually getting around to offering the iPad) isn't such a great idea either.