New iPhone app: Fire Department:

It prompts you to ask if you’ve been trained in CPR and would be willing to help a stranger in the event of an emergency. If you accept this, then the application will take advantage of the iPhone’s location monitoring to get a general sense of where you are (a new feature enabled with the most recent update allows this with a minimal amount of battery drain). Then, the next time a 911 dispatch center receives a call for an emergency that’s occurring near you, you’ll receive a push notification telling you that help is needed. The app will also tell if you if an automated external defibrillator (those electric paddles that can kickstart a heart) is nearby.

(via New Initiative Harnesses Smartphones To Help Keep Heart Attack Victims Alive)

Regarding CPR’s effectiveness:

Used alone, CPR will result in few complete recoveries, and those who do survive often develop serious complications. Estimates vary, but many organizations stress that CPR does not “bring anyone back,” it simply preserves the body for defibrillation and advanced life support. However, in the case of “non-shockable” rhythms such as Pulseless Electrical Activity (PEA), defibrillation is not indicated, and the importance of CPR rises. On average, only 5–10% of people who receive CPR survive. The purpose of CPR is not to “start” the heart, but rather to circulate oxygenated blood, and keep the brain alive until advanced care (especially defibrillation) can be initiated.