How to disable WhatsApp group message notifications? I'd like to only receive notifications (in the notification-bar) from single contacts but I don't know how to disable them without disabling all notifications from Whatsapp (via Settings->Apps).

Does anyone have a clue how to accomplish this?
The only way to mute group messages is to mute them for a time period, and the maximum duration is 1 week. To do this, open the group conversation you'd like to mute, press menu and select Mute and then select the desired duration (8 hours, 1 day, 1 week).

Unfortunately this means you have to do this weekly and separately for all groups.