I expected something different and it doesn't worth the time spent.

Didn't read the entire book (reviews say that some essays are badly written) so I chose the following list:
Berkeley DB. Well-written and contains good pieces of advice. But it's very sparse.
HDFS. Nothing useful to anyone who knows what NameNode is.
NoSQL Ecosystem. It's not about architecture. It's an outdated review of NoSQL solutions.
Python packaging. Interesting from a historical perspective. What to say? Modules in programming languages is not a solved problem and in Python's case it's complicated by legacy.
Riak and Erlang/OTP. Well, Erlang has means for client-server communications. They're called behaviours and you can implement a server using it (aka write your own middleware). That's it.
Selenium WebDriver. The first page of google gives better insights.
* Sendmail. It's a history of long-dead problems with email. It might be interesting if you use sendmail, but I doubt it.