It would be a really helpful feature if I could have workflows trigger based on when another workflow runs. I can imagine a lot of ways this could be useful!
Additionally, based on particular criteria happen but a workflow not running.
Can you give a specific example?
I believe you can already accomplish this, albeit not via a direct/explicit tie to the trigger workflow. You can have the last step of your trigger workflow write some value to a field. Your next workflow just looks for changes in said field.