Engadget does an amazingly bad job of linking the original article. You would think that the sentence 'Bloomberg Businessweek just published an amazingly thorough piece on Nokia' would have a link in it, but it doesn't.
No where on the page do they link to the start of the original story. The 'source' button links to the page/paragraph that the quote is from, but that isn't exactly the same as linking to the front of the other article.
The only links in the content go back to other Engadget stories. I'd say its bad etiquette.