nothing added for a 'basic' user (if you mean email and calendar only). 3.6 does email and calendar syncrhonization wirelessly. 4.0 adds in the functionality of a few other things. for those who care about being able to open images in their email, then you'd want to consider 4.0. from an admin's standpoint on server and handheld management, 4.0 is lightyears beyond 3.6.
__________________ In the beginning the Universe was created. This has made a lot of people very angry and is widely regarded as a bad move.