@mike finley -
The site owner will know about it. There will be an email sent to the site owner/admin.

The risk that a minor update breaks anything is very small. The policy is just to fix serious vulnerabilities and severe regression issues of the main release. Latest versions of external libraries, like jQuery and the like, will not be included in minor releases.

Finally, automatic updates will only take place about 12 hours after anyone will have had the opportunity to do a manual upgrade, giving time to stop the automatic update if anything breaks after all.

Unattended sites getting hacked due to publicized vulnerabilities is a much bigger problem. This great enhancement has come to combat this.

Take a look at http://wordpress.org/plugins/update-control/ and live more safe/dangerously.