Although a good DSLR will help you avoid perceptible shutter lag; the problem with a DSLR is that you can't fit it nicely in your back pocket!
Camera Tip #11: Avoiding Shutter Drag
Many digital cameras have a slight delay from the time you press the button until the picture is actually taken. Many new digital cameras have improved and have a very minimal delay but none have reduced this time to zero. The delay is caused by the camera adjusting the focus, exposure and color balance. This may cause you to miss the exact shot you were hoping for. By framing your subject and pressing the shutter button halfway (and holding it there), the camera will have taken its readings. This prepares the camera for the shot that will be captured when you fully depress the button. This is the best way to avoid shutter drag.