I've started using perlin noise for camera shakes instead of using spring-like solutions. It gives a similar result visually and will be completely frame-rate independent.
Spring/physics style solutions have a habit of behaving differently or even catastrophically falling apart when you run at very low or very fast frame-rates. Of course, that can be fixed by running that bit of the simulation at a fixed frame rate, but that didn't fit in nicely with my camera code which was independent of the fixed-rate update part of my simulation so for me, perlin noise was less hassle.
I suppose you lose some control though - e.g. with a physics based solution you could push the camera in a specific direction (say, in response to an explosion or bullet impact) and have it return. With perlin noise, My only control is fading in and fading out the shakiness.