Very jealous. Pretty much what the others said. Especially Cali and Beanie. Gwen will shove anything out of the way if she can. She will also jump into your lap, nudge your hand, paw, whatever. (Boyfriend taught Gwen the wonderful "UP UP" and now she feels like she can jump in your lap WHENEVER.)
What Cali said about the cats is what happens with Gwen, too. We have a cat that lives with us and if I even look at the cat, Gwen comes running. I'm evil too because I think it's pretty hilarious to watch Gwen try to chase the cat off. She starts trying to act all tough and growls and whines and circles him. They haven't actually had a tumble. She just paws and tries to mouth him. She is getting more adventurous, though. "Oh you were outside? Welcome back" *TACKLEMOUTHGROWL*
Gwen is just an odd one. We've even considered getting another dog so she can learn some humility.
I equate her to a spoiled only child. And Charlie (the cat) is like the foster kid we didn't intend to keep. And I think Gwen knows that!