My understanding is that media and copy may be subject to copyright, but not layouts of websites. I don't think copying a wireframe CSS design or page navigation mechanics or general theme is legally copyright infringement (I could be wrong).
It depends on how unique the copied is and how similar the copier is.
From a decision about magazine covers: "None of the individual elements [...] ordinary lines, typefaces, and colors — qualifies for copyright protection. But the distinctive arrangement and layout of those elements is entitled to protection as a graphic work."
