The one thing that I learned from the "talking heads" during the Boston wall-to-wall coverage was that there is 'public safety' exception' to the Miranda rulings. As with most legal questions I have, I contacted an attorney friend who explained that this exception dated from a Supreme Court decision in 1984.

For those who are interested, Wikipedia has a description of the decision, including its background and suggestions for further reading:

http://en.m.wikipedia.org/wiki/New_York_v._Quarles