A working closet is one in which you can remix what you own into infinite cute outfits. A closet that doesn't scream "go shopping now!" at you every time you walk in. One that knows when a new piece is needed and when it's time to let an old one go.
In other words ... organization. So that people like me, with seemingly infinite supplies of clothes, can stop standing in front of our closets frustrated thinking OMG, I HAVE NOTHING TO WEAR. Because how lame is that? Anyway, the series is awesome and you should read it:
Part I
http://kendieveryday.blogspot.com/2010/12/create-working-closet-part-1.html
Part II
http://kendieveryday.blogspot.com/2010/12/create-working-closet-part-2-assess.html
I can't wait to see the rest of the series!