The ShareLaTeX Cloud Compiler was shut down on the 21st of July (Github Sync in the ShareLaTeX editor will continue to be supported). We hope this won't cause a big workflow change for most people, and we're really sorry if it does.
The ShareLaTeX Cloud Compiler integration with Github has not been heavily used. As a result, it has not received much attention from our development team and bugs have started to appear over time. Rather than continue to support this underused feature we thought it was better for our users to continue to focus our development efforts on the core ShareLaTeX experience. Note that the GitHub sync available within the ShareLaTeX editor will continue to be supported and improved.
Our github sync inside the ShareLaTeX editor is still live and fully supported.