This is a very interesting article @ THeSeverSide.Net.
Daniel Cazzulino compares the features and functionality of EIF (Enterprise Instrumentation Framework) to that of the Open Source port of log4j called log4net. It’s a close fight but log4net wins out based on its simplicity and extensibility.
http://www.theserverside.net/news/thread.tss?thread_id=27317