Currently, you can still quick scope in Modern Warfare 3. Keep in mind though, multiplayer is always changing at this stage (new perks, new balancing, new everything all the time based on feedback), however our philosophy on that hasn't changed since MW2.
I think the most interesting aspect of this answer is that he made it clear that IW's opinion/philosophy on quickscoping hasn't changed since MW2. In case you didn't already know, Bowling has often stated on Twitter that he believes quickscoping takes skill.
