On a level with Christmas-themed Lemmings, if you apply the Bomber skill to any Lemming with a permanent ability (tested with a Climber and a Floater), the explosion is green rather than red.
If the Lemming is falling when you apply the skill (so it explodes instantly) or is otherwise highlighed at the point of detonation, the explosion is blue - this happens whether the Lemming has a permanent skill or not.
POST SCRIPTUM: Tested with version V10.011.011-D.
The latest V10.012.012 experimental has fixed this issue for bombers. I forgot to fix it for stoners too though; that will be fixed in the next experimental (and certianly in the next stable version).
EDIT: It's now fixed in the source. So will be fixed with next update, whether exp or stable.