[Status-bydesign][1] is the response to a bug/feature request stating that this is the intended behavior.

[Status-completed][2] means the feature/bug fix has been implemented.

[Status-declined][3] means the feature request is "rejected" and will not be implemented.

[Status-norepro][4] means a bug cannot be duplicated

[Status-planned][5] is a feature that is being planned.

[Status-review][6] is a bug/feature being reviewed.

[Status-reproduced][7] is a bug that has been successfully reproduced.

I'm not sure what [status-deffered][8] is intended to mean.

I believe there is also a status-accepted (though there are none currently) which would be when a feature request has been accepted, but has not been completed yet.

  [1]: http://meta.stackoverflow.com/questions/tagged/status-bydesign
  [2]: http://meta.stackoverflow.com/questions/tagged/status-completed
  [3]: http://meta.stackoverflow.com/questions/tagged/status-declined
  [4]: http://meta.stackoverflow.com/questions/tagged/status-norepro
  [5]: http://meta.stackoverflow.com/questions/tagged/status-planned
  [6]: http://meta.stackoverflow.com/questions/tagged/status-review
  [7]: http://meta.stackoverflow.com/questions/tagged/status-reproduced
  [8]: http://meta.stackoverflow.com/questions/tagged/status-deferred