Steam For Linux Now Available To All Users ~ Web Upd8: Ubuntu / Linux blogGreat job on making Steam for Ubuntu there, Valve, but (boo! hiss!) on not including the damn key with the installation so people can actually update it when they install it.
This blog mentions how to fix it, with the command below:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F24AEA9FB05498B7