Smokie Bares All
Sorry for the ramblings that follow but I have a lot of things spinning in my head right now as I get back into Lost mode.
First, what do we really know about the smoke monster? Based on Locke telling Ben, “Sorry you had to see me like that” it would appear that Smokie is taking the form of John Locke. Likewise, from Jacob saying “I guess you found your loophole” it would seem that he is also the ‘man in black’. He obviously is at odds with Jacob and based on the conversation in the season 5 finale it would seem that he views people as a ‘lost cause’ (could that be the real the meaning behind the title ‘Lost’?). This would help to explain why Eko was killed when he refused to repent for his life of destruction and death.
I like the idea that Smokie is related to the earth's elements and is bound by water. This raises some interesting questions though. First it means that the Looking Glass was "off limits" to him. But we know that Jacob hates technology so the idea of it or the need for it wasn't from a message from Jacob. It could of course just be a Dharma station that the Others took over, but it would seem as if there is more to it than that. If smokie is actually part "defense system" then are the Dharma sharks intended to serve a similar function for the Looking Glass?
I like the idea that Smokie was imprisoned on the island. If you can't cross over water then an island would be the perfect jail cell. Is he imprisoned and longing to go home? Did Jacob imprison him (or is his desire to continue the loops in hope of a change prolonging their time on the island) and that's part of why smokie has such hatred for Jacob? Being imprisoned would start to explain the destruction of the trees - a temper tantrum maybe?
An unrelated thought- what was the deal with Desmond? When he sat with Jack on the plane he was very cool and together. That's in stark contrast to the often jumpy, nervous and less than confident sailor who so desperately needed Charles Widmore's approval. There has been a lot of speculation about what happened to him after Jack saved Charlie. Was he jumping through time? Did he really know who Jack was?Is it the same Desmond or is he an alternate being like the rest of them? (I had assumed he was immune to that since he is able to time shift and as we've learned - and in contrast to what he's been told - he can change events.) Of course this is based on the idea that we're not seeing an alternate universe, but an alternate reality of the same people.

Smokie couldn't bear it
Yeah, I think all those identifications are true Smokie=Fake Locke=MIB. In the overall arc of the show he/it represents entropy I think while Jacob represents Mind (I'm gonna try and write up some more thoughts on that--but the Mind versus entropy idea came out of what I wrote about "Some Like it Hoth.")
I'm not sure that we know that Jacob hates technology. That information might have been about whoever was in the shack, and I think that that was Fake Locke.
I do think he's been imprisoned on the island in various ways at different times. Another mythological identification I have for him is Loki--who was imprisoned underground and when he's freed it is the beginning of Ragnorok (the end of the world--or at least the end of the gods).
The destruction of the trees--something I'm going to add into that same post--but I think the trees on the island are Bodhi trees? The ones associated with the tree of life. I think it's where bodies (like Paul's) got buried (and that's why Horace was blowing up trees). That's a way that the island/Jacob takes in the individual mind/spirit and makes it part of the Mind. Smokie on the other hand--uses the body. So I think blowing up the trees is destruction of these mind/Mind connections. Sorry if this is very sketchy--some of this tree stuff is also in the discussion thread of "Horace hears a..."
Desmond--well I did realize over the weekend that he has a motive to bring the two worlds back together in that there's no Penny in the no crash world (Widmore would have been killed in the explosion). So I wonder if this is the no-crash-world Des (in the crash world Penny still exists)--and does he have conscious connection with his other self? Also realizing that we still don't know Des's parentage. I wonder if he was one of the kids that got taken off the island before the explosion? I've always thought that his affinity for places like monastaries and the army spoke to having been raised in an orphanage.