It seems like only a short time ago that Linden Lab made the Second Life Viewer open source. Since then many developers have created viewers that violate the terms of service in the virtual world of Second Life such as allowing unrestricted copying of objects, etc. It has become such a problem that Linden Lab will begin suspending and banning developers who create viewers that violate either the terms of service or the community standars. Soon new guidelines will be created as well as a registry of approved viewers.

Read more here.