Next chapter's flashbacks are from Desmond, the name of the chapter is "Catch-22".
The promo is on youtube (it's always there):
http://youtube.com/watch?v=ycGZg-HpmAg
And there is a sneak-peak too, but it's kind of spoiler, I'm just warning, you can watch it on youtube, though its only 1 minute long you'd maybe prefer not being spoiled xD
One interesting thing, is that in the promo video you see it says something like Ardil 22, which is Catch-22 in Portuguese
(remember those portuguese guys in the last chapter of the second season?
)
I'm glad I speak spanish, there is a great site about lost (lostzilla.net), with tons of information
