You may be wary of making your location available to apps and services on Android, but that uneasiness goes away in an emergency situation. If you call emergency services, you want them to know exactly where you are, and now Android has the tools to make that happen. Well, if you live in the UK or Estonia. Those are the first two countries with support for the new Emergency Location Service.

When you call in an emergency with this service active, your location will automatically be transmitted directly to first responders (without passing through Google). It can use GPS, network, and WiFi location for the most accurate reading.

This feature is being deployed as part of Google Play Services, so you won't need to do anything to enable it. It will, however, require proper carrier and emergency services support. That's why it's only in the UK and Estonia right now. Why those are the two first countries is not clear, but Google says it wants to expand the Emergency Location Service to more regions later. Over 99% of Android devices are theoretically able to support this feature via Play Services (Gingerbread and up), but carriers and emergency services need to work with Google before it can expand to more markets.