1. No one cares if you take Dustin's concept that pre-published posts should be called "ideas" instead of posts and have lower overhead. He told us all about it, he gave it away. Open source it, it's a great idea, everyone should be able to host their own blog and have as little overhead as possible in nurturing ideas into posts.
2. It is wrong to take someone's design and just use it for yourself. It seem especially shitty to do this when someone has announced they are going to try and make money off of using that design as a brand. This obviously gets pretty grey pretty fast but there is a line and this copy crosses it. It's cool to use other people's work to guide your own, that's how we learn. But when you take something, you have to make it your own. Imagine if I took kottke's css and changed the bars on top from blue to red, it would not only be wrong but silly. Aping someone else's style is not how you want your blog to be remembered.