Google announced a new feature for the mute this ad option on the ad units.

When you click on the “mute this ad” button, it will ask you why you want to remove the ad and then it will count down from 3 seconds and hide the ad. After the ad goes away, the content below the ad, may rise up as the ad unit collapses.

Here is a diagram from Google on how it works, and I tested it on some sites and it does work:

Google said:

It is pretty cool.

Forum discussion at WebmasterWorld.