http://news.msn.com/us/you-can-now-send-texts-to-911-in-an-emergency-1
It’s not as efficient as immediate help from people around you, but if you REALLY REALLY GOTTA TEXT, assuming you can use your fingers, then you can text to 911 along with your location and your emergency. Of course, this won’t work unless you have texting service. Smart phones don’t automatically have a stress beacon.
It’s only available for certain regions right now, but service is provided by major providers AT&T, Sprint, Verizon, and T-Mobile.