If you haven't heard about all the controversy — not about the book, but about the US cover — a good summary (with links!) is at YA Highway.
The thing is, the book is about a liar. OK, maybe you got that from the title. But Micah, the main character, lies the whole way through the book — except to the reader. She promises — over and over again — that everything she tells the reader is true.
One thing she says is that she's black.
The US cover showed an Asian/white girl.
Apparently the publisher didn't feel a black girl on the cover would "sell" well. Not only the author, but many of her fans, got justifiably upset about this — after all, if the main character was lying about such a basic thing, it calls into question everything the main character says in the rest of the book (like Atonement, but not in a good way). In the end, such a big stink was raised that the publishers decided to change the cover to the one at the top of this post. (The masses triumph again!) Still not a very black black person, but I think she says she's three-quarters white anyway, so to me that's still believable.
If I decide to buy this book, there's no way I'm getting any cover except the new US one — just to show there's no reason to discriminate like that.
The controversy's got to be good for it, though. There are so many people who never would have heard of Liar without the controversy. And the author won through in the end, so all's well that ends well.
Finally, to help us poor readers to decide whether we'll like it, Ms Larbalestier (I think that is such an awesome surname, by the way. I don't know how you pronounce it, but I like to roll it like "lar-bar-LEHST-ee-yeahh") has put an excerpt of Liar up on her website. So if it sounds good, but you're not too sure, go check it out!
And happy (belated) release date to Ms Larbalestier!