Document Layout Analysis - state-of-the-art?
After some research, I came across ICDAR (International Conference on Document Analysis and Recognition), which is taking place biannually and seems to be the most complete and up-to-date source for state-of-the-art document analysis algorithms.

ICDAR is hosting a competition in different subfields each year. At the time of this writing, the latest results from ICDAR 2015 have been published as Competition on Recognition of Documents with Complex Layouts –
RDCL2015. (Search online for a PDF version.) This paper describes state-of-the-art document layout analysis algorithms, and compares their performance to both open-source and commercial solutions.