Just want to clarify...
Registration is not a requirement
for copyright, it just gives you some advantages. Lack of registration does not equate to a surrender of copyright.
From the U.S. Copyright Office's "Copyright Basics":
In general, copyright registration is a legal formality intended to make a public record of the basic facts of a particular copyright. However, registration is not a condition of copyright protection. Even though registration is not a requirement for protection, the copyright law provides several inducements or advantages to encourage copyright owners to make registration.
I suggest every photographer spend some time on this web site.
[Edited 2003-12-08 17:02:40]