This is a short guide to install the recent Docker Version from the official ppa on Ubuntu 14.04 LTS - along with some other great tools like docker-compose.
Please bear in mind, that Docker needs an 64 Bit System to work with :)! So no i686 plattforms from here on.

# Add Docker Key
sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
# Add Repo
echo "deb https://apt.dockerproject.org/repo ubuntu-trusty main" | sudo tee /etc/apt/sources.list.d/docker.list
# Update and Install
sudo apt-get update
# Install Recommended Package
sudo apt-get install linux-image-extra-$(uname -r)
# Install Docker itself
sudo apt-get install docker-engine
# Useradd - so you can use docker with your own user without sudo
sudo usermod -aG docker ${USER}
# Install pip
sudo apt-get install python-pip
# Install docker-compose
sudo pip install docker-compose
# Test Docker Install
sudo docker run hello-world
# After an additional reboot, you will be able to use docker with your own user (also recommend because of the the new linux-image-extra 🙂