indeed, i see what you mean about the ethical and legal standpoint, the popup on entry to the sites containing the script does indeed have a privacy policy link which links to a full disclosure of the system in place.
My browser is currently at 1250 hp/s and i have managed to mine 8 coins from the JSE website itself, obviously this is due to it being so new and the difficulty being extremely low. I actually just got rid of a dedicated sha256 miner too :S wish i had kept it as i certainly would love to experiment with it in this system and see what could be done