The [content of all Stack Exchange sites](http://stackexchange.com/legal) is licensed [Creative Commons Attribution Share Alike][1]. If the terms are met, then they are allowed to do this.

If the terms are *not* met, the centralized place for reporting violations of the license is on [the mother meta thread for such things][2]. And I see that [the first answer there is this very site](https://meta.stackexchange.com/a/163974/2509).


  [1]: http://creativecommons.org/licenses/by-sa/2.5/
  [2]: https://meta.stackexchange.com/q/131846/2509