Head on over to Stewart McKie's site. He has a new article on how best to protect your work - including how to register your script and a bit about a creative commons licence. All good stuff.
On a related note - I should just write down here what I tell students when I do a University guest lecture. I've seen more good scripts fail because people won't send it out for fear of someone stealing it - than I have seen scripts being stolen.
Ideas like 365films are ripe for a steal. But no one has after 2 years.
Still from Eight.