OMG J! I thought exactly the same but i've kinda come to the conclusion after watching it agen that its the guy from the others who ben sent to their camp, i cant remember his name of the top of my head (ben asks how long it will take to get to their camp and this guy in question says "well if i take my ten best..." you know who i mean??)

Ryan Pryce, but he is with his 'ten best' trying to go the Losties camp isn't he, as we see him in the trailer.

yeh but the way i take the trailer is they get to the beach camp and the losties plan doesnt go as they hoped and they get captured... thus explaining ben saying "shoot them" so ryans behind them preparing to go all execution style on them... you see where im coming from??

Yeah, I see where you're coming from. Guess we'll just have to wait and see.

I take back what i said, on closer inspection it seems that ryan is close to the camera as ben says shoot them and it could well be john locke making a comeback behind sayid... but he appears to have changed his green t shirt from the last time we saw him (and about time too!)

I think it is locke, now i've looked a couple of times and there plan must have gone kinda right because on the trailer you see like 5 getting blown backwards from the explosion. I also think locke comes back and tells ben he is still on his side, Ben belives him and then ben says shoot them and locke shoots ben and his goons.

Well, I've had a look on the cast list for the episode and Terry O'Quinn who plays John Locke is definitely in the episode, but whether he's still alive or it's a flashback is really anyone's guess!

i've just saw the trailer and i'm 100% sure it's Locke.

My first instinct was also that it was. But I paused it and realised it is definately Pryce. However, I'm sure Locke's not dead, because he was shot where his (now removed) kidney should be, thus merely making a painful hole in his chest. How he'll get out of that hole I don't know, though. Maybe he'll make a ladder out of bones.

Giovani... i thought it was ryan myself but from closer inspection of the view we get it very much looks like locke pointing the gun, im not saying that it definately is locke for the simple reason i dont know but what i can say is it definately looks like ryans shoulder/lower head on the right hand side of the screen in the frame we are talking about...

can u guys tell me from wer did u watch this episode that locke appears in?????....because i really wants to see if it's him...

It's in the videos section for this spot, the trailers for the next episode.

i saw that video..... 90% its locke....but why does he want to shoot sayid and the good ones.....after he was shot by ben....do u think that he will shoot ben and the man beside him?

It just doesn't seem subtle enough for the producers of Lost just to put him in the trailer. If he is alive, it would be quite a surprise, so they'd leave it until the episode.

Then again, maybe they thought that the final surpise is so immenseley surpisingly awesome that it didn't matter how much they spoilt in the trailer because the eventual episode would make up for it. I really hope that's the case.

Edit: I just made a comparison. The man's shirt is significantly lighter than the shirt Locke wore when he was shot (maybe he got changed). The shirt also appears to be untucked - and I'm yet to see Locke be radical enough to do that. You also have to wonder where Locke got that gun from.
Image:
link

My guess is that it's either Pryce or Jason:
(link)
But I'm not ruling out the possibility it's Locke.

Ok loook.... This scene which we are discussing, it flashes up right after ben says shoot them, there are two figures in the for-ground of the shot and you can make out sayid, bernard and jin on their knees facing these two figures. There is also another figure in the shot, which we speculate could be john locke.... The "john locke" figure i can say definately doesnt look like ryan pryce because, to me, it looks like his shoulder/lower head is one of the for-ground characters, the one with the tatoo. im almost certain that this one is pryce so this rules out the possibility that he can be the one behind our losties preparing to shoot them... bo ya bring back john "rambo" locke