It would be wrong if NateW hacked into and stole the source, or stole the design source/code of Dustin's project. But reproduction of someone else's work isn't ripping them off but is a compliment (it means that it's worth reproducing).

As good as Dustin is, neither his ideas or implementation of his blog/cms platform are that unique.

Follow that line and you will end up with two to three websites in the whole world of internet. He did not rip it off, in fact I see it as a favor for the original author, since its clearly stated that the second work is based on the first. If I release an HN simply for handful of people who I think are worthy of using it, then I should be dead ready for a crazy torrent of HN alternatives.