Yet they are under the CNN.com domain name, not cnnusercontent.com . therefore CNN.com 's reputation should suffer for it. (hello, Google PageRank team!)
Google penalizing a site for inaccurate user-generated content would be a pretty awful precedent. Stuff on iReport is flagged as "not verified by CNN" fairly clearly, as far as I can tell, and if CNN wants to sink its brand this is hardly the first salvo in that attempt.
That's explicitly stated. "The stories here are not edited fact-checked or screened before they post." http://ireport.cnn.com/about.jspa