Having taken more than 1 compact digi apart, I can safely say that Canon fit dust seals around the differing barrels of the lens. This should keep the dust out (Canon are not the only manufacturer to do this btw). Could be that the dust id just flakes from the motor and gearing that work the lens optics for focus and zoom. As has been said above, a sharp tap on something semi-solid (such as your wrist) should dislodge anything significant.

Incidentally, the optics of some of the compact cameras are something of miniature miracles. I am in awe of the designers and process engineers who think out the way to assemble these things