Oops - my fault. I forgot that we changed the driver again and you need to download the latest from CVS at sourceforge, recompile it for PG 7.1 and take off from there.
We decided that we would change empty strings to NULL in the driver FOR BIND VARIABLE EMULATION ONLY. This helps a lot. Since the bind variable hack isn't part of SQL but purely a database API thing, it's not as awful a hack as it first appear (awful enough, though). Without this hack you would have no way to insert NULL at all using bind variable emulation, clearly wrong (because the driver quotes all non-empty strings, which would cause NULL to become the literal string 'NULL', not all that useful).
We need to get our documentation act together...
Anyway, I do believe this will help you get to the "official" point of failure with PG 7.1.
