Rack as Unix pipes?

At the Rails online conference “Exploring Rails 3” (http://en.oreilly.com/railswinter10) early this morning Australian time, one of the most useful things for me was a coverage of Rack - what it is, and how its thinking & approach now permeate much of Rails 3 (currently in beta).

Yehuda Katz (http://twitter.com/wycats) was manning the chat room, and posted this awesome compilation of his thoughts on Rack and the “pipeline pattern”.