I have tried numerous ways to get iphoto to print two or four pictures per page with little success. You can change the number of images across the page from one to two or more using the slider, but it calcualtes internally the number of photos it will fit verticaly. Everytime I have tried to layout two 4x6 or two 5x7 pictures, I only get one per page. The same seems to happen with four photos unless I make the images fairly small and waste almost half the page.
And even if you are printing 16 images per page it sets the space between each image WAY to high. Other programs I have used squeeze them toghether much better, Including Epson's junk software. I look forward to version 2.0