OK, the first caveat to this is that I have not passed the Bar (yet, I hope), so this does not constitute legal advice, only my opinion (it's an ethical thing). Second caveat, I only got a B in Intellectual Property law, so take this with the appropriate grain of salt.
All that said, I'm not entirely sure you can copyright a pattern in and of itself any more than you could copyright a recipe (for more knitting and cooking, see my blog post for tonight). I would liken a pattern to a formula, which can definitely not be copyrighted. When people put together books of facts, like encyclopedias, they have a copyright over the exact presentation of those facts, not the facts themselves.
In addition, independent creation is a defense to copyright infringement. If you lived in a cave all your life then happened chistle out Harry Potter and Deathly Hallows on your wall, well then JK's out of luck. Of course, this is a pretty tough fact to prove, but there it is.
So, that's my 2 cents. Man, I should've gone to more class...