What can be copyrighted?

Since taking the course on Ethics and Intellectual Property at Chalmers I have become increasinlgy interested in how copyright and patent laws affect software development. United States of America have different patent laws compared to western Europe, usually more obliging of what can be patented, but the legal rulings in the former concern also software used in the latter.
Just a few days ago the verdict in the case of Oracle v. Google regarding copyright infringement on Java API was determined with the concölusion that it is not possible to copyrigth an API, but certainly the implementation of it. A summary of the verdict was written by the judge, William H. Alsup, and is most interesting to read. I think it shows a great understanding of the context of software development from a legal perspective.

Watch an interesting film about the american patent system and software patents: Patent absurdity.