I found this entire book online last year (through ERIC): Primary Writer's Workshop: Developing Process Writing Skills.
It has some good management ideas and is a quick read. You can download/save it to read from your computer. (Click on the book title for the link.)
Another book I found online is Vicki Spandel's Seeing With New Eyes. I just stumbled across it yesterday, so I haven't read it yet. It's a long one--over 300 pages. It's about assessing primary writing. (Click on the book title for the link.)
A couple of resources online that I think are very useful.
Jessica Meacham's site (Melissa mentioned this one at the workshop. Lots of minilesson ideas & forms)
Picture book inspired lessons at Writing Fix
Lesson plans and powerpoints for teaching using writing workshop
Diane