I do believe that Patrick Jane is in fact Red John and believe I have some fresh insight in this case. As we all know, Patrick is very well-read person. He knows the entire play Hamlet (S04E20), and Jane very cleverly misquoted Macbeth and Philo fell guiltily into his trap by correcting him that it was “Neptune’s oceans” not “Neptune’s waters” (S04E17). Now, we all heard (S02 final) Red John tell Jane a poem by William Blake: The Tyger. Obviously this was not really Red John saying this, but another accomplice of him. However, we do know that both RJ and PJ like poetry,

I know it's far from airtight, but add everything up (everything being things that were previously said such as both of them being master manipulators, Red John knowing a memory from Patrick's youth, Patrick's frequent daytime napping, Red john knowing the 7 names and Red John always being a step ahead of PJ) and I believe it is safe to assume Patrick Jane as Red John. I do not believe PJ is aware of his alter ego, but I do believe RJ is aware of his alter ego.