Homebrew: HOWTO for the great OSX package manager

In this session I will discuss the brief history of Homebrew, why it was created (instead of just using Fink or MacPorts) and how to use it. I'll mention the technologies used (Git/Github/Ruby) and the project structure. Finally, I'll encourage people to get involved and show how to create new packages (known as formulae), how to submit new packages for inclusion, how to create binary packages (known as bottles) and where to find help with any Homebrew issues.
This presentation should be a useful and entertaining overview of the core elements of Homebrew and introduce people to the tool. It should be useful to anyone using OSX (or considering helping with the Linux port) to provide them with quick and easy package management. I'll assume a technical audience but no in-depth knowledge of any particular technology. There should be new and useful information in here from complete novices to Homebrew contributors.