We use it to run a bunch of periodic report-building tasks. Compute internal metrics, archive support tickets, that sort of things. Compared to plain cron, we get proper tracking and history of the runs that failed, and a web UI to access the results (generated reports, for us).
I wouldn't use it for production-sensitive crons, but for administrative stuff, it works fine.
Absolutely - we (i.e. engineering @ Simon) view Jenkins as crontab that's easier to maintain, to track historical runs, and to keep tabs on failures (with full logging).
We do at my work. It has much more robust options. You can keep multiple jobs from running at the same time if one takes too long. You can auto kill it after a time limit. You get a web UI for all logging from the job. You get great built in tools for auto deleting logs after a certain number of builds or time period. You get a very robust email solution for sending out alerts when jobs run or don't run or fail. It adds some complexity vs CRON but it has many more features.
We have tried that as it is easy to learn the status of the job and view logs. But had problems while running many jobs simultaneously. Some jobs will hang. So now we are using Cron + Monitoring External Jobs Plugin in Jenkins(https://wiki.jenkins-ci.org/display/JENKINS/Monitoring+exter...). This gives the performance of Cron and the above mentioned advantages of Jenkins.
Yes, We do. We primarly use it as Job scheduling engine. I have multiple teams asking for data extracts, and I fashioned Jenkins to run extracts both adhoc as well as fixed schedule basis.
I wouldn't use it for production-sensitive crons, but for administrative stuff, it works fine.