New psql doesn't case-fold in \d command:
regression=# \d DEFAULT_TBL
Did not find any relation named "DEFAULT_TBL".
regression=# \d default_tbl Table "default_tbl"Attribute | Type | Modifier
... etc ...
I'd expect the name of the table to get folded to lower case unless
I put quotes around it. That is in fact how 6.5 psql behaves.
regards, tom lane