Currently Being ModeratedNov 21, 2012 12:35 PM (in response to Liz Castro)
The viewport size I use is 512px wide by 768px high for my individual .xhtml pages. For a two-page spread this would mean the viewport is actually 1024px by 768px.
Yet I paint my original images for a Children's Read Aloud Fixed Layout ePub at 2048px wide by 1536px high and then cut the painting in half for a two page spread. This means on the new retina display, my images will look great yet be backward compatible with the original iPad.