archive_timeout behavior (8.4.6)

Hi all,
We thought we were having issues with our warm standby (postgres
8.4.6), but think we figured it out, however I'd like someone to confirm
what we think is true.

If a cluster has zero activity whatsoever, but we have archive_timeout
set (say to 60 seconds), will it create a WAL file anyways, or knowing
there was zero activity does it skip it? We turned it on (temporarily)
to force WAL files to go to a newly set up warm standby so we could
verify that we have the whole end-to-end process correct, but we didn't
have any WAL files transfer to the warm standby. After some trouble
shooting, we notice that we do get a WAL file shortly after we insert a
single row into a table.

The confusion is probably because I remember this same scenario on older
versions of 8.4, and watching it generate wal files even with no activity.

So long story short, if a cluster has zero activity, and archive_timeout
is not set to 0, when it reaches that timeout should it generate a file,
or just skip because it would be 100% empty?

Thanks in advance,
Brian F