I was quite surprised to see that I haven't restarted the iMac running OSX Leopard for almost 18 days.

It's incredible that this thing doesn't need a a reboot more often - I'm using it for .NET development in VMWare Fusion, Ruby On Rails Dev with NetBeans, MySQL, MonoDevelop + Mono, writing, web browsing and recording in Garage Band. So, it's not exactly light use