logging arguments to prepared statements?

Dec 18 15:49:41 myhost postgres[29832]: [35-1] ERROR: 23505: duplicate
key value violates unique constraint "foo_key"
Dec 18 15:49:41 myhost postgres[29832]: [35-4] INSERT INTO foo
Dec 18 15:49:41 myhost postgres[29832]: [35-5] (a,b,c)
Dec 18 15:49:41 myhost postgres[29832]: [35-7] VALUES ($1,$2,$3)
Dec 18 15:49:41 myhost postgres[29832]: [35-8]

And that's it, leaving me wondering which value triggered the error. Any
way to tweak postgres to include the values too, without setting
log_statements=all?

changed log settings:
log_destination = 'syslog'
log_error_verbosity = verbose
log_min_error_statement = notice
log_checkpoints = on
log_connections = on
log_disconnections = on
log_lock_waits = on
log_statements = 'none'
log_temp_files = 0
log_autovacuum_min_duration = 250

other log_* settings kept as default (commented).

PostgreSQL 8.3-beta2 (FreeBSD port is lagging behind a bit).

Thanks.