Yidong Chong (maintainer of Emacs) has posted a patch here: list-processes reimplementation, and list/menu buffers So list-processes will be implemented in elisp in Emacs >= 24 and thus this package is not needed for Emacs >= 24.
When M-x list-processes, I usually want to kill a stuck process. It'd be easier to add features to list-processes if it were implemented in elisp. See the discussion in emacs-devel.
(require 'emacs-process)
NB: after loading this package the C version of list-processes is renamed to list-processes-primitive.