I have started a booklet on Pharo, hopefully the first of, um, more than one. It is entitled RedditSt20, on my fork and extension of Sven Van Caekenberghe's excellent "Reddit.st in 10 elegant classes", to cover the following in another 10 or so classes:
The book is being written using Pillar, of course. Note that the Pharo 5 version of Pillar that I downloaded from InriaCI doesn't work - the supporting makefiles aren't able to obtain the output of "./pillar introspect <something>". Use the Pharo 6 version.