To add to the above: you've got to use what the publisher can process into their internal intermediate format. They'll then process that into PDFs, e-books, print, and whatever other formats are ultimate required. Your tools need to enable you to productively edit text and mark it up correctly (according to the publisher's stylesheet -- which usually has little to do with what the document will ultimately look like and everything to do with what each piece of text represents).

The OpenOffice info there seems to be out of date -- they have a pretty good OpenOffice.org stylesheet. I wrote my two O'Reilly books ("Fedora Linux" and
"X Power Tools") in OpenOffice.org that way.

OOo is a pretty reasonable choice, especially with a custom stylesheet, because it is XML-based and can be transformed into other formats.