Copyright Assignment / Sharing

There are lots of different projects that require copyright transfer in order to contribute.
MySQL is another example of a project that requires copyright transfer. 

Another example is Apache foundation asks for copyright assignments.

There are a variety or reasons why you'd want copyright assignment. 

A couple examples from GNU include that you don't have to worry about legal representation..
the only people that can go after license violations are the ones that own the copyrights. Of
course GNU offshoots like the Freedom law foundation have made it easier for independant
programmers to get that sort of representation.

Another example is if you want to have more licensing flexibility. GNU will let individuals or
projects have special exceptions for code they want to use from GNU software.. Like Gnash is
based on public domain-licensed software and if the original author wanted code back they
would be willing to do it. In this way GNU is often much less licensing-nazi-ish then they
seem at first blush. It's much easier for people to negotiate with them then, say, Apache
foundation for licensing compatibility issues. 
People like MySQL or Trolltech will have proprietary versions of their software available for
people that do not want to abide by the terms of the GPL for whatever reason. 


Of course with out the copyright assignment a project can track down the original programmer
and get special exceptions, but that is a lot more tougher and most people don't want to deal
with that on a individual basis.


This seems to be what Sun is after. They want to be able to change licensing terms to suite
customers or third party software company's demands. This is normal stuff and I don't think is
something that is worth being alarmed about.