I don't like the fsevents idea. Apple did this for Spotlight. If you want to hook into that, you have to do it as root. Bad idea. Also, the queue can get clogged, there's only one buffer for all clients, and if anything else happens on the system - expanding VM for example - then the system sends a different event instead, namely that it's currently unable to send events [sic]. I figure at least 50% of those capable of upgrading to Tiger have not done so for well documented reasons, and at any rate this way of doing things works better, faster, more reliably, and it works on all platforms.