The use of a ob-core file is necessary to avoid circular requires.  If
Emacs Lisp provided for actual modules which could be split across
multiple files we could simply have every core ob file as part of the
same module.  However given the limitations of Emacs Lisp as a language,
I think this is the cleanest approach providing for both separation of
functionality across files, and simple requiring from the outside.

>
>> Finally this consolidates Babel defcustoms into ob.el where they will be
>> more immediately brought into scope, and are more easily maintained.
>
> Yes, if you merge the files; otherwise, I'd stick to the namespace 
> rule: defcustoms belong where their namespace indicate they belong.
>

Agreed.  I won't consolidate the defcustoms.  As long as we're requiring
all of the files in which they live this should not be a problem.  Also,
I agree that future maintenance is eased by keeping defcustoms alongside
the code in which they are used.

-- 
Eric Schulte
http://cs.unm.edu/~eschulte