https://twitter.com/getB3NT/status/404963267896172544If you swear in a private Skype call on the Xbox One you get this half-sentence: $500 console
Edit 1:
He says it happend during voice chat and it was detected through Kinect:
https://twitter.com/sidspyker/status/404978449250414592/photo/1
Edit 2:
Apparently, it's not just swearing during a skype call that results in a ban. Swearing during a video you record and upload can also result in a ban. It apparently gives you a 24 hour ban.
http://forums.xbox.com/xbox_forums/xbox_support/xbox_one_support/f/4274/t/1628408.aspx?PageIndex=1