The A12 28mm lens hood is sold separately and at the moment, it appears to be very limited item. I would suggest you to ask at popflash.com. They don't have it listed, but they may know something more about its availability?
The lens hood (LH-1) is being given out for free when you purchase the A12 28mm lens in some parts of the Asian-Pacific area, you might try to look on eBay or Yahoo! in Taiwan / Hong Kong / Japan to see if anyone is selling theirs.
At the same time, you might also look at some alternative 40.5mm lens hoods, for example, those for Leica or other classic cameras (a cheap cone here: http://cgi.ebay.com.hk/40-5mm-Lens-Hood ... 0352245768), which I have bought one just for laugh, but it also works in the same way I suppose. :lol:
I'm from Singapore and I can verify that we do NOT get the LH-1 with the A12 28mm. As in Europe, this remains an optional accessory that has to be bought separately. I've spoken to various store owners and some people from the local forums and they say they did not received the LH-1 with their A12s too.
Early bird buyers of the 28mm module in HK get the hood for free.
Mark that when using the built-in flash (I hadn't tried the external flashgun), the hood has to be taken off to avoid its shadow appearing on the lower part of the final images.