Feb 3, 2011
Arduino 0017 or later
While the individual libraries are downloaded within a single archive, they do not depend on each other (unless noted otherwise) and can be used independently.
The libraries are published under the GPLv2 (or, at your discretion, any later version).
Also, by popular demand, I've prepared a very simple demo sketch using DNS, DHCP and Bonjour together. Basically, it gets network configuration data via DHCP, then lets you resolve DNS names via the DNS server received from DHCP, all while announcing its DHCP-assigned IP address via link-local Bonjour — Basically a combination of examples from the individual libraries, which I also recommend to look at, as they contain lots of comments explaining how stuff works.
To install the libraries, you need to place the folders contained within the download zip into your "libraries" folder. You can find it within your Arduino IDE distribution within the "hardware" folder. Be sure to restart the IDE if it was running.
On a Mac, you will want to create a folder named "libraries" in in the "Documents" → "Arduino" folder within your home directory. Place the folders contained in the download zip there (and restart the IDE, if it was running during this process).
Additional information can be found on the Arduino website.
Since this involes hardware, just a small disclaimer that I'm not responsible if you destroy anything while tinkering with these libraries.