Requires commitment, offers fantastic resources
Community Review for NaNoWriMo Young Writers Program
My Take
Make no mistake, writing a book in a month will require considerable commitment from you and the students. This website allows you and your students to sign up and access a class page and discussion forums with other students who are taking on the same challenge. There are also plenty of teacher resources and some extremely useful workbooks to help the students brainstorm.
How I Use It
I have used the teacher's resources from YWP with my after-school Authors Club as well as my regular classroom. The first year I tried it, none of the students felt they had finished their stories in a month (which was fine, since our program ran all year). The next year we used the site as a supplementary resource but extended the first-draft-writing period from October through December, which was more doable. For an English/Language Arts teacher who wants to use this in a classroom and complete it in November, my suggestion is that you would likely need to have the kids working on this almost exclusively for that month.
The workbooks, by the way, are simply amazing. Not only do they help students understand how to effectively use dialogue, create character, build tension, etc., but they help readers understand how authors do these things in the texts they read. If the Common Core has you focusing more on author's intents and choices, explore the writing workbooks for ways to teach this from a writer's perspective and then have the kids look fore these techniques in what they read.