This would be an extremely nice feature.
We currently use another tool that performs this function. I found that it is possible to create a monitor in that tool, and then schedule and run it from VisualCron as an http command - a condition is used to check the output for the result that would result in VC taking some action on it.
It would be much nicer to have this integrated into VC, and based on a trigger, rather than frequently scheduled checks.