Just that Tobias Mehler will be playing Zak on episodes 4x18, 4x19 and 4x20. What does this mean? I have no idea (and I really wouldn't like to find out before watching it so please say "spoiler" if you're talking about it in the comments). This are just my thoughts: Could it be that when the end is aproaching Kara, Lee and Adama think about him? Or does this mean something else like that he's alive or a cylon or something?
Anyway, it's always good to know we'll have more Zak before the end of the series, huh? =)