My article on How We Wrote the TT Book Using TT has been published on perl.com.
Of course I'm slightly biased, but I think it's an interesting look at a non-trivial and non-web use of TT.
While the article is an interesting piece of read, it looks like you've been reinventing the wheel a lot. DocBook addresses all those problems you were trying to fix and is in general a more appropriate format for writing technical books, than POD. With all these Perl hackers together, DocBook might have been less fun though. :)