The book is coming in a month. One big reason why there aren't a lot of Django books out there is because instead of trying to make money off of books, they focused on writing high quality documentation to begin with. That book that's coming out is free online as well: http://www.djangobook.com/

The reason there are lots of Rails books is because there's a lot of hype around it. That doesn't necessarily mean the community is more supportive.