Your question has already been answered but I'd thought I'd give you a quick bit of advice. Id advise buying books for amazon and sending them to the kindle app you can download from the app store. Not only is amazon often cheaper, but that way you can read it on all devices linked to your amazon account.
In answer to whether you can transfer the purchase to another account, that is a no no. For obvious reasons. If a company allowed that only one person would need to buy a book and then they could send it to everyone else on the planet if need be. I know this is an exaggeration but it's still a moot point.
Proud owner of a 32GB wifi iPad2 iOS5.