Mongrel, just to clarify, the runaway log file (growing log file) is a Leopard OS bug. Has little or nothing to do with WD. My fix in the referred post was for getting it deleted and restarting the ASL database so it would return to normal. There are hundreds of threads on this bug in Google. The fix is generally the same as the one I posted, (which was the easiest one I think)
EDIT: This is probably the best article on the buggy syslog issue I have found and incorporates the fix (or close to it) that I recommended.
http://dans.im/blog/archives/8 although I also suggest a restart and repair permissions after you fix it, as they are usually the culprit at the beginning of the process that leads to the bug rearing it's head

Google: leopard syslog cpu ... or runaway system log Leopard
Most folks only experience this vary rarely, usually after a nasty crash of some sort. Apple is aware of the bug and I am sure is working on it.
All the best,
Jmar