Currently Being ModeratedJun 15, 2012 11:23 PM (in response to ellieoday)
There should be a Purchased tab at the bottom right of the Store page in the iBooks app which should show your past ibooks purchases (those that are still available in the store) - if you go into that tab, the books which have a cloud symbol next to them are those which aren't currently in your iBooks app, and if you tap that symbol next to a book then that book should download onto your iBooks bookshelf (and the cloud symbol should change to 'downloaded').
Currently Being ModeratedJan 3, 2013 2:04 PM (in response to ellieoday)
I'm in the iBooks app on my iPhone 4 and when I go into the "Purchased" tab, I get "You do not have any purchased books available to download." Accessing the iTunes Store via iTunes on my laptop, I have two books listed under the "Books" tab at the top; however, these books do not sync when I connect my iPhone to the laptop.