For me, a hobbiest heavily invested in canon gear...
I use both.
Raw - gives you the most data to manipulate on the cameras firmware, canon digital professional or Lightroom. The raw file must have a copy saved as a JPEG for most people who don't own a camera to use.
JPEG - gives a file that can be saved to any computer right out of the camera, but some limitations on what can be done in post processing. And, degrading of the image with each manipulation (I haven't been able to appreciate the degradation, but many experts agree that it does).
So, say your out at some Navhda event, and your shooting some dogs in the field. Your buddies brought their laptop and want some of your awesome pics for Facebook or whatever. If you shoot JPEG, you can fill their hard rive with your pics and they can make the images smaller with default computer programs for Facebook. If you are shooting raw, they need you to process the files and upload them to flickr, or save to thumb drive or a disk or something for them to get the pics.
Regardless of method, no post processing can save an out of focus pic...
