I'm not buying Charlie is a part of "the others". We basically know that Ethan alone and that Kate and Jack were closely tracking them. So, Ethan must have "brainwashed him" or something really fast, and then after taking the time to covert charlie to otherness, he goes on to kill him. Why would he want to kill him if he was trying to get convert him??? And do it all in record time knowing that Kate and Jack were right behind him. Sounds like a bit much. I think that when Sayid was talking to him, he wanted support and Sayid may be on the fact that Charlie knew where the guns are. Sayid is a logical man. I think he knows that Sawyer couldn't have stolen the guns alone, and who logically would help him...someone who who has nothing to lose and wants to get back at Locke. I just think Charlie being an other is wat out in left field.