Still Lost

So...it's what?  Four more episodes.  Where is this thing going?  How are they going to wrap up all the story lines and hanging threads in four episodes.  I hate to admit this publicly, but I'm going to go hit the boards and see if there are any spoilers out there.  Surely somebody can explain the polar bears.  And wasn't there a virus that killed some of the tailies?  Does Jack really have a son named David, or is it just in the one parallel time line?  How was it possible to kill Jacob?  What/who is Smokey...I'll be glad when this is over.