[http://www.debian.org/devel/debian-installer/ Debian Installer] installs discover and hotplug by default.
Hardware Autodetection at Boot
Discover
The development of Discover is led by [http://www.progeny.com/ Progeny] and it has its own homepage: http://platform.progeny.com/discover/
Hotplug
Even though hotplug wasn't mean to handle coldplugging it can handle it nowadays. Hotplug doesn't have it's own database of module mappings (it uses the running kernel's modules.*map) and will therefore never get outdated.
Kudzu
One widely used hardware autodetection and probing tool is ["Kudzu"]. It was initially developed by [http://www.redhat.com/ Red Hat]. Kudzu loads modules, generates dev links. Kudzu stores information about the hardware in [hwdata http:''/packages.debian.org/hwdata]. Knoppix's hwsetup-knoppix component is based on Kudzu.
hwinfo is the hardware detection tool used in [["SuSE"] Linux http://www.suse.com/]. It's currently packaged (in Debian) in a way so that it can't handle hardware autodetection at boot, but the maintainer is willing to add the necessary stuff to make it possible.
Currently, Hotplug is the only mature software to handle hotplugging.
xdebconfigurator can set up X automatically by using different backends. Check the package dependencies for a list of possible backends.
Project Utopia is a vision of how hardware should be handled in Linux. It currently consists of [http://packages.debian.org/hotplug hotplug], [http://packages.debian.org/udev udev], [http://packages.debian.org/hal hal] and [http://packages.debian.org/gnome-volume-manager gnome-volume-manager]. [http://packages.debian.org/dbus-1 dbus] is used as a layer of communication. udev needs a Linux 2.6 kernel to work. By making /etc/hal/device.d/fstab-update.sh executable you let HAL handle fstab and mountpoints dynamically. HAL comes with some small nice tools like lshal and hal-device-manager. Project Utopia is basically supposed to tie together lots of stuff into something that creates a nice end-user experience. hwinfo
Hotplug
X Autoconfiguration
Project Utopia