Now that I've had undistracted time to look at the covers, I'm back to make more comments!!
1. Harry's Scar: Definitely visible on the UKC cover (thanks, fish, for the abbreviations!). I think you can see the bottom of the scar, as fish said, in the US cover as well, as that part is going the opposite direction of his hair.
2. The Sword: Here's the description of Gryffindor's sword:
"silver" with a handle "gleaming with rubies the size of eggs", and has Gryffindor's name engraved on it just below the hilt
So, I'm guessing that it's not Gryffindor's sword, though for some reason that would make sense to me.
3. The Elf: Now that I can see him!

Has to be Dobby. I doubt they'd have let Kreacher have a sword while behind them, and they don't look worried enough about him for him to be anyone other than Dobby.
4. The Locket: UKA looks cool, but not really anything too out of the ordinary. I think it just shows the importance of the Horcruxes in this book, and as this is one we know for certain, it's the most likely candidate to put on the cover. On the US version, it probably is the locket, but it looks more like a pouch of something to me. Looks like it's tied at the top. Maybe I'm getting too desperate for something, but it just doesn't look like a locket.
5. The Deer: I still think it's the patronus and not Prongs. Notice he's kind of smiling. . .
6. The crystal ball snake: Also has a window in the reflection of the crystal ball. Don't know if that means anything or not, maybe it points to being up in Trelawney's classroom. . .Don't know.
7. Hogwarts and brambles: I think the brambles are new, perhaps sent to guard something (or I could have just watched sleeping beauty way too many times). (The dog, definitely Bloombury's symbol, having nothing to do with HP.) Whether it means anything or not, there seems to be a full moon. Looks like most of the lights in the castle are on.
8. The armor, helmet, etc on the UKC front: Looks like a dragon on the armor to me, too. The beak-like face points more to a dragon than a snake.
9. Trio: Aside from them being all beaten up, don't Ron's and Hermione's faces look like there's something there, waiting for them? Something unpleasant? I'm trying to figure out if there's any significance on what's reflected in Harry's glasses, but so far I'm drawing a blank.
10. The curtains, US. Definitely not the veil or the death chamber. Here's the description of the Death Chamber and the veil (I'll bold the clues that it's not the veil):
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This room quite large and also rectangular. It is dimly lit. In the center is a sunken stone pit some twenty feet deep. Stone benches run all around the room and descend in steep steps toward a raised stone dais in the centre of the pit. An ancient, crumbling stone archway, unsupported by any surrounding wall, stands on this dais. This archway is hung with a tattered black curtain which flutters very slightly as though it had just been touched, althoughthe air in the room is still and cold.
Aside from that, it looks like they're outside (clouds in the sky). Could be magic, but I think, like fish, that they're someplace new.
11. Whatever it is they're reaching for on the US cover, Voldemort's eyes are definitely not on whatever Harry's looking at. Voldemort's eyes are looking toward Harry while Harry is focused out of frame.
12. I'm not wholly convinced that the lumps in the background are actually people, but if they are people; they're the Death Eaters. They're not floating like Dementors.
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I would be surprised by the latter, because of the little importance rowling has put in divination thus far.
It really wouldn't surprise me, though, because though, on the whole, we have gotten very little positive commentary on Divination; Rowling has used it for a few important plot pieces: The prophecy and Peter's return to Voldemort as well as the cards in HBP.
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Did anyone else think that the jewels shown on it were non-cannon?
I agree with this. I mean, if there'd been that many emeralds on it, would Merope have been swindled as badly as she was as far as its worth? I doubt it. HBP ch. 10 gives us that it was "a heavy gold locket." From ch. 13 "it had [Slytherin's] mark all right" again from ch. 20 "a heavy gold locket" and "'Slytherin's mark,' he said quietly, as the light played upon an ornate, serpentine S." Nothing about jewels . . .
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4) I would say that this locket might be the fake locket. remember that harry started carrying it around at the end of HBP as a talisment and a reminder of his task. Perhaps this develops into a full-flegded neurosis. Or the locket could be the destroyed slytherin locket. Perhaps harry put it around his neck to taunt voldemort. It's a very simply, nonverbal way of saying "I destroyed your horcruxes." That would be very cool.
I agree with this, as well. Since it most probably is the locket around his neck; I'm sure it would be the fake one as the other one needed to be destroyed. Dumbledore didn't have the ring after he destroyed that Horcrux, so I'm thinking there'd be naught left of it when he was through
Oh, one last thing, and then I'll stop, I promise! Notice in the treasure that the only gemstone is the ruby. Still makes me thing of Gryffindor. Rubies are flying about. Rubies are in the treasures. Gold and rubies, plus the silver of the armor; plus the helmet also has a ruby in it. Hmmm. . .
(Sorry I didn't follow any kind of nice concise order!)