Sorry for delayed reply, but we've had Internet problems.
Yes, it does work. What you do is register a new device to your Amazon account under Settings, Manage your Kindle, Register a Kindle (you can have up to 7 devices registered to your account). You add the Kindle/iPod/iPhone/tablet to your account (you'll need the serial number of each device), and they will show up under Your Devices. When you then buy a book, you can choose which device you want it delivered to. For example, I bought one for my husband a couple of days ago, and selected his Kindle for delivery. Now if I want it on my Kindle, I'll go back into My Kindle Library, select the title, and under "Actions" ask for it to be send to my Kindle. Then it will be removed from his Kindle and sent to mine.
So only one of the registered devices on your account can read it at any one time, but you can keep switching it between them. The book can only be sent to one of the devices registered to your account; you can email it or transfer it any other way that I know of to any other account, because the ebook is linked directly to the serial number of the device to which you sent it.
I don't know how the Goodreads sharing thing works, so can't help there, I'm afraid.
I hope that helps. :)