All the cameras (or almost) have a low-pass filter between the lens and the CCD (or CMOS) imager.
As the CCD is monochromatic, the camera has a RGB filter in a RGBG pattern (the bayer pattern) between the CCD and the lens. This means that a 50% of the pixels are used to capture the green info, and 25% for each the red and blue color. When the image is converted to JPEG, all the missing pixels are interpolated. To reduce the color aliasing artifacts of the bayer pattern in the image, the low-pass filter is used. This tend to a "softer look" in the image. To recover part of the detail, some cameras apply some amount of sharpening. Usually Canon prefer to apply a lower amount of in-camera sharpening that Sony or Minolta for example, and I think this is a good thing, because oversharpening the image destroy detail info. In fact, I use the S50 in the "low sharpening" setting, to obtain the image with no in-camera sharpening when I use the JPEG mode (I almost always shoot in RAW).
Always is better to sharpen in the PC with HQ sharpening algorithms.