Allmost all of the eBook market is based on free-flowing eBooks, but again most of the textbooks, children books etc., are fixed page layout books.
Preparing fixed layout eBooks are easier now thanks to ePub3 standard which is just being adapted by the industry.
There are not too many resources for the fixed layout books. The one I found to be very helpfull is: infogrid pacific Azardi. Thanks to these guys, I could finally manage to make an iPad friendly ePub3 Fixed Layout eBook, which I plan to write a series of tutorials on the details of the process.