The git hub repo is split in two:
contains the reusable libraries such as ethchain, ethwire, ethdb and ethutil
is the client itself (both the GUI, 'Ethereal' and a command line interface are included)
Go-ethereum of course makes uses of eth-go. The go implementation is versioned both by the use of Git Tags as well as version numbers displayed when the client is started.
As of POC5, regular binaries releases and pre-releases can be found on https://github.com/ethereum/go-ethereum/releases
. Where are the docs?
The full wiki can be found here: https://github.com/ethereum/go-ethereum/wiki
Basic CLI commands are listed here: https://github.com/ethereum/go-ethereum/blob/master/README.mdBuild instructions
The best thing about the Ethereal Go client is that it's very easy to get access to the latest and greatest features - you don't even have to wait for a binary to be released, or resolve complex software dependencies.
For specific instructions on OSX including building Edge, click here: http://forum.ethereum.org/discussion/905/go-ethereum-cli-ethereal-simple-build-guide-for-osx
Build instructions for all other platforms can be found here: https://github.com/ethereum/go-ethereum/wiki/Building-Ethereum(Go)
To build Edge (the bleeding edge version), follow the instructions here: https://github.com/ethereum/go-ethereum/wiki/Building-EdgeAll code is at https://github.com/ethereum/
Any third party sites linking to something else are likely scams.