Ubuntu has a very neat feature for this: Specialized repositories for different programs hosted on launchpad.net called PPAs (Personal Package Archives). You enable a PPA by appending the sources.list contents shown on the PPA page to the file /etc/apt/sources.list. More here

Gentoo and Debian basically don’t have any “releases” – updates come in frequently. When you wake up, turn on your computer, it tells you that there are updates, you install them and want to start working – and bang, one of theses updates breaks your apache/ssh/ruby/you-name-it. Pretty bad for your productivity.