A design blog on typography, page layout, graphic design and logos, including a well-known post on page proportions.
HN links it mostly for "The Secret Law of Page Harmony," which prompted comments on paper sizes such as US Letter and on Gutenberg's printing innovations.
Gutenberg didn't invent a machine for quickly producing books, he invented a machine for quickly producing machines for quickly producing books!
That is, his key innovation was a way to mass-produce the characters (the movable type) which could then be arranged to mass-produce the printed pages.
First, individual characters were carved from steel (each taking about a day to make). This was the only part of the process done "by hand". Every other element of the process was produced through some form of (repeatable/arrangeable) transfer of shape/information.
The master characters were hammered into brass to create a mold which could then be reused to cast multiple copies of a character. Each page had thousands of characters and Gutenberg's shop had multiple presses going at a time, so they needed lots of these characters on hand (50,000 is a conservative estimate).
The masters could also be easily transported to another city. These masters (plus raw materials of course) were all that was needed to set up a new print shop. This enabled the printing press technology to quickly spread throughout Europe.
I think it's a good analogy for the power of software :)
Source: http://retinart.net/beautiful-things/gutenberg-book-changed-world/
U.S. Letter size predates the European standard. The U.S. Letter size apparently originates with vellum sizes and was originally intended for handwriting not typography[1].
However, there are some good ways to use 8.5 x 11 [2] that might look odd on narrower and taller paper.
[1] http://marginalrevolution.com/marginalrevolution/2012/09/why-8-12-x-11.html
[2] http://retinart.net/graphic-design/secret-law-of-page-harmony/