One better does. I found in our company meetings, done by Skype, that I can mute people in a team conference, which I do if they are to noisy. I guess sometime they will have trouble to unmute themselves again, but I guess one has to know his/her shit to master it.

Yes, we had been using GoToMeeting and recently moved to WebEx. Typically everyone is pretty good about muting themselves, but I don't usually eat during these meetings, so I sometimes forget myself!

Does it have a mute per default, similar to Mumble or Teamspeak with a push-to-talk button (at least the first one does have it)?

With WebEx, you click a mute button which is just a toggle. The host does have the ability to mute people, either all, or individually.