Is there a PPA or Repository we can add to our system so that we receive automatic updates to our Ethereum software in GNU + Linux?
From the Ethereum Foundation: https://launchpad.net/~ethereum/+archive/ubuntu/ethereum
There are 2 primary PPAs,
ethereum for stable releases and
ethereum-unstable for develop builds of Geth. From Go Ethereum Downloads
they are updated automatically.
ethereumPPA is updated when a new version of the latest release (currently 1.5) branch is tagged.
ethereum-unstablePPA contains "the develop snapshots of go-ethereum, updated automatically when a new commit is pushed" on the
Additional information from the Ethereum blog:
Beginning with Geth 1.5, we will no longer maintain a separate master branch for latest-stable and develop branch for latest-edge, rather we will switch to master as the default and development branch of the project, and each stable release generation will have its own indefinitely living branch (e.g. release/1.4, release/1.5). The release branches will allow people to depend on older generations (e.g. 1.4.x) without finding surprising git issues with history rewrites. And having master as the default development branch would allow developers to use the latest code.
For ArchLinux, you can get geth, mist and the webthree packages from the user repositories, e.g.:
yaourt -S ethereum geth mist