My DS8, is starting a gifted cluster program in August, but has many of these organizational issues too. Late, Lost and Unprepared mentioned above is really useful. Don't expect it to have all the 'answers', but it lays out the problems of kids with executive functioning difficulties (organizing/focusing), and puts out strategies to cope.
To be honest, I'm sure I was one of these kids myself growing up, and I'm delighted that it is now being recognized as a distinct difficulty that some kids have, rather than laziness.
One point it mentions is that all ADD/ADHD kids have Executive Functioning issues, but not all kids with EF problems have ADD/ADHD.
