WAL file location

I've developed patches to be able to specify the location of the WAL
directory, with the default location being where it is now. The patches
define a new environment variable PGXLOG (a la PGDATA) and postmaster,
postgres, initdb and pg_ctl have been taught to recognize a new command
line switch "-X" a la "-D".

Comments or suggestions?

I'm intending to head towards finer control of locations of tables and
indices next by implementing some notion of named storage area, perhaps
including the "tablespace" nomenclature though it would not be the same
thing as in Oracle since it would not be fixed size but more akin to the
"secondary locations" that we support now for entire databases.

There has been some discussion of this already but I'm not recalling
that someone has picked this up yet. Comments or suggestions?

- Thomas