Extending tablespaces

Recently I ran into a "disk full" problem with my database. I had to
play with the tablespaces and locations symlinks... until the disk could
be cleaned just enough for the database to continue operation. I had
plenty of space on another disk but found no *easy* way to humbly ask
postgres to continue using other empty disk.

I read the partitioning at
http://www.postgresql.org/docs/8.1/interactive/ddl-partitioning.html
but this unfortunately is not an option.

Now I am thinking what it would take to give pg the functionality to
extend tablespaces automatically.

Something like "ALTER TABLESPACE foo ADD LOCATION '/bar'" and then PG
can continue operation without notifying the disk is full...

I yet have to dive more deeply into the storage system to gain more
knowledge. I also realize that implementing something like this will
effect many things like VACUUM, pg_dump, indexing, sorting and the
entire storage system etc..etc..

I very much would like to know the communities opinion and thoughts
about this. Would this even be possible? Or I am just dreaming (again)
and scaring everyone else.

--
Regards,
Gevik Babakhani
www.postgresql.nl
www.truesoftware.nl