Despite not having a planned release date. I suggest we start speculating on what's going to be in Volume 41.
I predict 389-398 which will probably cover all of Robin's flashback (we won't know until 398 is released will we.)
The title will most likely be named after Chapter 391 "A Girl Called Devil"
On the cover will be Robin and Olvia embracing with Saul in the background and Buster Call going off.
NEW NEWS Feburary 3 2006: ocean has reported that One Piece v41 may not come out until April or later due to Shueisha's March Tanko list not having One Piece.
It's now most definate that 398 will be the ending chapter and Declaration of War will be the title.