Keith Adams explains how/where/why Facebook uses PHP, PHP's benefits (lack of state/programmer workflow/concurrency), efficient PHP with HHVM, the Hack project for optional typing PHP and much more.
Crista Lopes discusses the idea of using constraints to define styles of programming and architecture. Also: large scale static analysis of open source code, Open Simulator and VR, and much more.
Simon Thompson and Huiqing Li explain refactoring with functional languages and Wrangler (Erlang) and HaRe (Haskell). Also: how Wrangler's ad-hoc mode allows everyone to write custom refactorings.
Kostis Sagons talks about how type checking can help with a dynamic language like Erlang and how static analysis tools like Dialyzer or automated refactoring tools like Tidier help keep code clean.
Kevin Rutherford talks about the challenges of refactoring Ruby code, and his open source tool 'reek' which automates the discovery of certain code smells in Ruby code.
In this panel discussion from QCon San Francisco, several influential leaders of the software development community discussed and debated the future of the Java language and APIs based upon the lessons we have learned from the past. Topics included static versus dynamic languages, removing code from Java, forking the JVM, and the next big programming language.