checkpoint_timeout irrelevant in 8.1.9

According to the WAL config documentation correctly, checkpoints are created
every
<mk:@MSITStore:C:\Program%20Files\PostgreSQL\8.2\pgAdmin%20III\docs\en_US\pg
admin3.chm::/pg/runtime-config-wal.html#guc-checkpoint-segments>
checkpoint_segments log segments, or every
<mk:@MSITStore:C:\Program%20Files\PostgreSQL\8.2\pgAdmin%20III\docs\en_US\pg
admin3.chm::/pg/runtime-config-wal.html#guc-checkpoint-timeout>
checkpoint_timeout seconds, whichever comes first. However, it seems as
though setting my checkpoint_timeout has no effect on checkpoint creation (
I have it set to 30 seconds). Forcing checkpoint by running psql -c
CHECKPOINT mydb doesn't do the trick either. Checkpoints are created solely
based on the checkpoint_segments logs reaching their configured size.

This is not satisfactory in a low transaction volume environment. Any hints
on how else can I trigger checkpoint?

Thanks in advance,

~george