How do I silence incoming call and text message ringtone without hanging up in the Galaxy Nexus? I have set up MP3 ringtones for both incoming calls and text messages on my new Galaxy Nexus, but I can't figure out how to silence them without hanging up (in the case of incoming calls) or without having to wait until the entire sound bite is over?  Any suggestions?  Does anyone know how to do that?
Any help will be greatly appreciated.
When the Galaxy Nexus is ringing...

Tap the power button on the right side of the screen.

The ringtone will stop and the screen will switch off. BUT the call has not been hung up. 

You can even press the power button again to switch the screen back on and the ringtone is silent if the call is still waiting to be answered. The voice call will still be at the correct volume when you actually answer it.