package management revisited

Ages ago we discussed ELPA, the emacs packaging system. It allows you to
browse through an online repository of emacs packages and install, uninstall
and upgrade them, all from within the emacs comfort zone (menu:
Options/Manage Emacs Packages).

Emacs 24.1 (a pretest is available) will include a version of ELPA --
package.el; the version included with emacs 24 supports multiple
archives. The official archive is the one provided by GNU, then there is
the current one for ELPA, but there's now a third one available: Marmalade.

Marmelade ('Spreadable Elisp') offers a very easy way for developers to
make their packages available to emacs users, and an even easier way for
users to test out interesting packages.

To use all available package repositories (GNU, ELPA and Marmalade), add
the following snippet to your .emacs:

(setq package-archives '(("ELPA" . "http://tromey.com/elpa/") 
                          ("gnu" . "http://elpa.gnu.org/packages/")
                          ("marmalade" . "http://marmalade-repo.org/packages/")))

This works out-of-the-box for Emacs 24; for Emacs 23, you'll need the newer
package.el, which you can get from the emacs 24 repo (if necessary, remove
the old package.el first).

Currently, there are 870 packages listed in the three repositories – a lot of
toys to play with! In fact, it is already getting quite hard to find what
you're looking for; a bit more structured way (maybe using categories) would
be useful. Also, a bit more information than the one-line description would
be very useful.

Nevertheless, it's a great addition to emacs, which will make it much easier
to play with packages – without even having to read the installation