I'm running 8.1.6.
BTW, I did a little searching on the postgres archives and I found out that using the 'FM' format option will simulate what I describe above.
openacs=# select to_date('2001 3 6','YYYY FMMM FMDD');
to_date
------------
2001-03-06
openacs=# select to_date('2001 03 06', 'YYYY FMMM FMDD');
to_date
------------
2001-03-06
Unfortunately, using dashes confuses it:
openacs=# select to_date('2001-03-06', 'YYYY-FMMM-FMDD');
to_date
------------
2001-02-22