My situation: I have a few hundred pages of files I made quite a few years ago, optimized for "self-publishing" via the printer. I no longer have any source files (my own bad). These files have 2 pages next to each other in an A4 landscape PDF. I would like to change and combine these files into a US Letter portrait PDF.
I have browsed earlier, similar threads, most notably the most referred to thread:
http://forums.adobe.com/message/3331516
which recommends using Adobe PDF printer. However, as this thread points out, and as I for one have found on my own system (10.8.3), Adobe PDF printer is no longer an option on Mac OS X (version 10.6 and on):
http://forums.adobe.com/thread/556366
So the question then is: How do we now split double-page landscape PDFs into single-page portrait PDFs?