symfony1 is well and alive and many developers are now using it for projects hosted on Git. But as the official symfony 1 repository is hosted on Subversion, it's not always easy to get things versioned easily.
As of today, this becomes much more easier. If you are using Git and symfony1, you can now use the official symfony1 Git clone.
This repository has branches for all symfony versions: 1.0, 1.1, 1.2, 1.3, and 1.4. And if you are looking for a specific symfony1 version, get any of the current 73 referenced tags.