Probably not, but according to Damon Lindelof, "When season five starts, you won’t know when or where you are. And the way we tell stories will be different too."
The video below was filmed (clearly without permission 
)at Comic-Con 2008 and can serve as a kind of season-5 teaser.
There are some other points about Season 5 here including the fact that Lost has apparently finished with Flash-Forwards & Flash-Backs 
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Josh Anderson's Blog 