Is it illegal to reproduce another website design?

Is it illegal to reproduce another website design both for personal and commercial purpose?

Let's say I like a website like engadget so much that I want to create my blog theme exactly the same way... or even that I like the apple site so much that I would like mine to look exactly the same.

Is it illegal to reproduce a design from another site into your own?

What about for commercial purposes? Let say you design a wordpress template that looks exactly like engadget and you decide to sell it. Any problem with it?

Your input would be appreciated.

Thanks,

J.

--
All is Grace!
~ Mother Teresa