I added status icons to the Salt Job Viewer today to make it easy to see when jobs have failed. The status is only checked for highstate jobs though.
To achieve this I added a new REST endpoint to obdi in a Go plugin to show and receive job status information. The Web GUI reads all job status items, and a shell script sets them when it notices a new job has come in (using inotify on the Salt job queue). The shell script runs forever and I'm running it from cron.
I've only just finished it so it remains to be seen how well it works.