Below is a list of links to various articles and resources for Standards-based Grading. These were provided by Kelly O'Shea.
In no particular order…
A few extras that didn't make it into my top 5 above
There's a lot more out there—these were the first things that came to mind in my search for implementation details, etc.
The details of my own particular implementation, real feedback I've gotten from students, some SBG theory, and my physics objectives are here: http://kellyoshea.wordpress.com/standards-based-grading/