PHP 5.6 has been in the wild for about a month now. As of October, the major version has received its first patch release 5.6.1 to address several bugs detailed here in the changelog.
Install latest PHP 5.6 on Ubuntu 14.04
sudo add-apt-repository -y ppa:ondrej/php5-5.6 sudo apt-get update sudo apt-get -y install php5=5.6.*
This PPA maintained by Ondřej Surý is quite stable and I have used the 5.5 repository in production systems for a while.