I have been in a departmentalized situation for several years now teaching 5th and 4th grades. Currently I teach fourth grade. I love this model because students benefit from the movement changing classes provide and if they don't mesh well with a teacher they are stuck all day with the same teaching style. For the teacher it means they can focus on an area where they excel----an area where they have more education. It also means less planning.
The state of Georgia is rapidly heading for inclusion which means all special ed students will be in a regular ed classroom and the special ed teacher will be in the regular room. Very few students will be self-contained in a special ed. classroom all day or even half a day. This may work for some special ed children but I see where we will have problems with many of the most severe students.