Well, as long as things are clearly defined in the package, I guess FHS compliant
package could be built with the same source tree.
We could even install a distribution the FHS way or the self-contained way,
as long as the tool knows what to put where.
But that is already the case, a bit:
For instance we have bdist_rpm, that builds rpms by mapping distutils metadata
to rpm ones,
The question is: starting with the current MetaData what would you miss to
do a FHS installation ? Take a look at
http://www.python.org/dev/peps/pep-0345/