Installing Node.js via package manager

Debian

Node.js is available in official repo for Debian Wheezy(testing) and Debian Sid(unstable).
For Debian Squeeze:

root@host: ~ # echo deb http://ftp.us.debian.org/debian/ sid main > /etc/apt/sources.list.d/sid.list
root@host: ~ # apt-get update
root@host: ~ # apt-get install nodejs # Documentation is great.

Ubuntu

Example install:

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:jerome-etienne/neoip
sudo apt-get update
sudo apt-get install nodejs

Warning : This seems to install a very out of date version (0.2.6)

On openSUSE BuildService

Node.js stable repos list.

Available RPM packages for: CentOS 5; Fedora 13; openSUSE 11.3 and Factory.

Example install on openSUSE 11.3:

sudo zypper ar http://download.opensuse.org/repositories/home:/SannisDev/openSUSE_11.3/ SannisDevBuildService 
sudo zypper in nodejs nodejs-devel

Arch Linux

Node.js stable and unstable are both available in the AUR.

Example install using packer:

packer -S nodejs

Also, npm (nodejs package manager) is available as an arch package. It can be installed through packer

packer -S nodejs-npm

or through yaourt (another aur tool):

yaourt -S nodejs-npm

OSX

Using a package

Simply download and double-click.

Using homebrew:

brew install node

Using macports:

port install nodejs