For a new codebase I'm working on, I needed to upgrade to PHP 5.4
My local VM that I'm working within is running 5.3, so here are the steps I went through to get up and running:
sudo apt-get install python-software-properties
sudo add-apt-repository ppa:ondrej/php5-oldstable
sudo apt-get update
sudo apt-get install php5
Care of: http://serverfault.com/questions/420286/how-do-i-upgrade-from-php-5-3-to-php-5-4-6-in-ubuntu