Originally Posted on the Blog: 
KiCad is an Electronic Design tool, much like EagleCAD. KiCad is free, open source software, and runs on OSX, Linux and Windows. KiCad is unrestricted. All features may be used for hobbyist or commercial works.
Here are some features of KiCad that might appeal to the hobbyist:
- Kicad Project Homepage
KiCad can be downloaded here. KiCad support on OSX is alright, but not as good as the other platforms.
For Ubuntu users: Adam Wolf maintains a launchpad PPA for the KiCad daily build. This build is generally stable, and months ahead of the "official" release.
- How to build KiCad from source
Wayne and Layne have a great article on how to build KiCad from source (on Ubuntu).
- Curious Inventor KiCad Guides
These guides are very comprehensive, and will get you up and running in no time at all. Unfortunately, they're a little out of date. For example, they still refer to KiCad as having no "undo" functionality, which it now does.
- Teho Labs Kicad Tutorial
Brian from Teho Labs wrote this great tutorial
- Dr. Johnathan Hill's Kicad Tutorials
Dr. Hill takes readers through an example project, which is a great way to get a good understanding of the workflow of KiCad.
This is the new tutorial on the block. It's not very well organized, but the information contained therein is very good.
- TransTronics Wiki
Again, poorly organized, but there's a lot of good info about general KiCad use here. Some parts are also a bit out of date.
EagleCad users are familiar with having large parts libraries available instantly. With companies like Adafruit, Sparkfun and DangerousPrototypes publishing high-quality Eagle libraries, it can be tough to transition. These resources should help you overcome that hump.
A highly respectable collection of library components.
- Open Source Hardware Engineering Community Library
Here you'll find all the default component libraries that come with Eagle converted for use in KiCad. Not all of them are 100%, but it's a great boost.
When you have to make your own part, this can really speed up the process. Provide some basic info, and download your schematic symbol.
- Footprint Builder
A Java program for quickly creating certain types of land patterns for KiCad components.
- Creating and Modifying Symbols for KiCad
This PDF does a good job of covering some of the more fiddly parts of creating and modifying symbols using the build-in editor.
KiCad, being free and community maintained, occasionally experiences some really annoying, fiddly problems. Below are the ones I've encountered.
Graphical Glitches on Linux
I experience graphical glitches on Linux, using any version of Kicad. When zooming in on a schematic, elements of the display pixelize, disappear, or become otherwise illegible.
I experience these problems on two computers, with different chipsets, CPUs, and graphics cards. After lots of troubleshooting and bug hunting, I've narrowed it down to an obscure interaction between my Xorg drivers, and the wxWidgets toolkit. I'm using the i915 graphics module (figure this out using lsmod). Bug report can be found here.
The solution is to Downgrade to the package of xserver-xorg-video-intel used in Natty Narwhal.
Tim Miller discovered another solution: http://comments.gmane.org/gmane.comp.cad.kicad.user/9949