You can use Alerts in your blogs. The standard alerts are:
Adding comment alerts
If you want to know when a comments is made to one of your blogs do the following:
Adding entry alerts
At the top of your blog, as a reader sees it, is an Alert me when this Blog is updated button. When a reader clicks this button and confirms that he or she wishes to receive these alerts, an alert is sent to the reader each time you add an entry.
Adding public to private alerts
The alerts as to changes from public to private (or vice-versa) are automatically in operation.