Layout is a subject that feels a little bit like a mystic art. There are really no books or accessible material about it, that I know off.
No, the TeX book doesn't count. Looking at the source of Chrome or Firefox doesn't count. Stretch source doesn't count. W3C CSS specs definitely do not count :-p.
I know that there are some papers floating (pun not intended) but I wish somebody wrote a serious book about layout algorithms! Even splitting the words of a paragraph into an optimal shape is something that is surprisingly more complicated and rich topic than one would imagine [1].
Do you know of any resources/docs/papers/implementation-notes that you would recommend?