> That would cause major breakage in the C API 

Not if you recompile. I don't see how this breaks the API at the C level.

> and is not inline with the intention of having a Py_UNICODE 
> type in the first place.

Py_UNICODE is still used as the allocation unit for unicode strings.

To get correct results, we need a way to access the whole unicode
database even on ucs2 builds; it's possible with the unicodedata module,
why not from C?

My motivation for the change is this post:
http://mail.python.org/pipermail/python-dev/2008-July/080900.html