A-ha! Just looked at the battery and indeed there is a tube connected to the battery, but there is already an "elbow" connected to it...all seems to be fine there. I'm guessing that there isn't another location for one of these elbows, this just might be a spare that was floating around or something?
Still no joy in finding out where this water is getting in from though. Just ran water over the door seal at the top/bottom, nothing came through and the carpet remained dry. Ran water through the drains and sure enough, it comes out on the floor of the garage. I may have removed a blockage the other day, not sure. I'm sure the next time it rains when I'm at work, or when I wash the car again, I'll find out for sure!
Oh yeah, I also checked out the floors under the seats...both are bone dry.
Cheers, Gord.