Overall, I think this was a fairly boring episode, but I think we can glean some fairly significant revelations from it, the least of which being Charlie's background. I think this episode, even though it seemed to center around Charlie, was really alluding to something else entirely.
I don't want to spoil anybody, so click inside for the full story.
So, if Charlie's not using heroin, and we have no reason to assume that he did use, why the fuck is he having crazy-vivid hallucinations? The only other time I can remember something simliar happening to anybody on the island was when Boone hurt himself and Locke made this salve out of some plants and shit. Boone had this wacko island acid trip not dissimilar to Charlie's. So, my theory is that Locke slipped Charlie some of the crazy salve somehow, maybe made more potent by the heroin (I'm sure he knew about it long before he "found" it in this episode...Locke is just like that).
Why would Locke want to do that? Well, I don't think I blogged about it, but one of my thoughts about Locke is that he has no allegiance to the other crash survivors. He's totally into the island, and he'd do whatever the island asked him to do. The island is his god. I forsee that sometime in the future Locke is going to defect to the Others. Now, I'll ask again, why would Locke want to drug Charlie? I think the answer is that he wanted to do exactly what he did, make Charlie lose face in front of Claire. Locke is subtly trying to work his way in with Claire in order to eventually take Aaron himself. He'll justify it by telling himself, "It's for the island." This will ultimately lead to a confrontation of the "Man of Faith" (Locke) vs. the "Man of Science" (Jack) and the other Man of Faith (Eko).
Furthermore, why is Locke keeping the heroin locked up in the safe? Why doesn't he just destroy it? Maybe he really likes porcelain statues? And why did he change the combination to the safe? Who knew that combination besides him and Jack?
Another curious happening in this episode was Hurley and Libby's conversation. If Libby was in the tail section of the plane, and Hurley was in the front section, and Hurley was the last person on the plane, then how did Hurley step on Libby's foot? I think Libby is lying, but I'm not sure why.
Why in the hell is Eko marking trees? I have no idea.
I have heard through the grape vine that there is no new episode next week, but instead they will be re-broadcasting "The Numbers" episode. The new episode in two weeks will apparently be closely related to that.