Gwen definately needs to come back for season five. Her characte was cool, even if she has only been in a couple of episodes. Her story could be very compelling to tell. She's like Rogue on the X-Men, neve being able to touch anybody. but now with this new gadget that she swiped, this could create a whole interesting story. The way she copes with finally having human touch and creating a bond with someone for the first time. Plus, there was quite a bit of sparkage between her and Gunn (literally and metaphorically), and I think that needs to be dealt with more.