iWeb 1.0 and 2.0 are alike in that they both store the information about your site in a file named domain.sites. In iWeb 1.0, all the information, including the XML for the page template, was stored in that file. One day a clever developer realized that you could “reassemble” a brand new template if you read the domain file carefully, separate out the pages and created an entry in the template list. For a year and a half, that’s how I was able to create custom layouts. I just built a site in iWeb, pushed the button and let the little script chop up my domain file and reassemble it into a new theme.

However, when iWeb 2.0 came out, the architecture had changed. The information about the page’s template is no longer stored in that domain file and at the time of this writing, no one knows where it went. Sneaky Apple :) So, we no longer have the ability to generate themes this way, which means, all themes have to be duplicated from an Apple theme and then hand-edited to change the hyperlink colors, image positions, border sizes, fonts, etc. Custom layouts would take hundreds of hours of hand-editing which just isn’t realistic.

That’s why no one can do custom layous right now. It’s unknown if it will ever be possible in this release.