You can get the latest release of the Social Connect plugin from here.
This is the recommended way of getting your copy of the plugin.
The recommended way of getting hold of the Social Connect plugin is by downloading the latest release.
If, however, you want to contribute to the project, then we suggest you fork the project from the current source code. It might be unstable and sometimes not work properly, but it will make it easier to integrate any changes you propose into our development process.
The source code of Social Connect is maintained in a Git repository found here.