The book MEL Scripting a Character Rig In Maya by Chris Maraffi, is an intersting book on how to automate more of the rig creation (something I am a big fan of). Maraffi has a video describing his tools on youtube at http://www.youtube.com/watch?v=x4s6-ahJWvU. This is a good book for those interested in MEL scripting and rigging, and has some more advanced concepts (such as creating a full UI for the rigs and some tools to create and bind rigs to a mesh.
Overall, the majority of the book covers the creation of a basic FK rig to a more complex IK rig, with a lot of focus on MEL scripting and setting up the GUI. The end result is a very nice collection of controls and GUI elements to drive the character, as well as some neat more advanced controls/scripts for handling the character’s breathing, eye jitter and stretchy spine.
While it would be ideal if the code base was in python instead of MEL, it is understandable that this is still the most popular Maya language. The code base works and has a lot of comments which will help the beginner, but is also fairly reliant on its own naming conventions, which also results in a lot of magic strings to keep the code together. I also feel that the code may have benefitted a little by being broken into smaller, simpler functions. There are a number of cases where a function seems to do a lot, and while it is easy enough for those with a developer background to understand, I always feel that fairly long functions are more difficult for the beginner to wrap their head around. The Maya GUI programming is pretty straight forward, it is easy for a Maya GUI script to get quite messy, but Maraffi does a prettty good job in keeping everything organized and logical with the GUI examples.
All in all, a good book and good examples and code base of rigging in Maya. I would recommend it to those interested in rigging and MEL script, although would recommend those following along with experience in python to look at converting the scripts to that instead.
I am really enjoying automated breathing in the rig, it is pretty cool.