I have used Moodle for four years now, and have tested version 1.6 in my classes enough to say that it is stable and ready for production sites. Bug-testing is thorough and fixing is fast. What I like best about this open source program is the user community. It supports innovation and contributions from teachers and developers all over the world. It has been adopted by the largest university in the world (Open Univ. UK--over 150,000 students) and yet is easy enough for a single teacher to set up with a couple clicks on a hosting service using Fantastico. I am now working with six other universities to make new modules--Project Module, Feedback Module, Mobile Phone Modules and other contributions. Imagine the next version, 1.7, which will begin repositories for teachers to share materials.