I have a multiply nested namespace:
namespace first {namespace second {namespace third { // emacs indents three times // I want to intend h
With c++-mode in Emacs 23, I had to do like this:
(defun my-c-setup () (c-set-offset 'innamespace [4])) (add-hook 'c++-mode-hook 'my-c-setup)
To disable the indentation in namespaces altogether, change [4] to 0.