Intelligent Flapping Detection

It would be great to see some intelligent flapping detection with the ability to alert upon a number of up/down or alerts over a period of time.

For example, there might be a host with a warning level alert that goes up and down - we may not be overly concerned with a warning for a brief period of time, however, it could be of concern if it occurs 5 times in 20 minutes.  At that point, we'd want the alert severity escalated to an error.  "5 warnings triggered in 20 minutes = error" or "10 errors triggered in 20 minutes = critical".  Something to that effect would be helpful for illuminating problems that we might not otherwise have investigate thoroughly.