I set most of my Iman jobs to a concurrent instance of 1. When a job tries to run and can't because the "failed to acquire semaphore lock or maximum concurrent job count reached" error occurs, the error is written to the errors.txt file but no email is sent out to the audit group. That makes sense, because there are probably a lot of customers who would hate to receive an email every time a job doesn't run for this reason. 

BUT for certain jobs, this error is our first indication that the job hung and will not run again without a server reboot. It would be really great if we could choose to send an email out if this error occurred. I'm thinking you could add it as an option to the Audit tab of the job. 

(This solution would also allow you to bypass my earlier request where I asked if you could tell us what jobs are currently running. If I had this option, knowing what jobs are running would be a nicety, rather than something that I really need. So you could wait on adding that until you were bored and/or wanted to give yourself a migraine. =)

Thanks!