I Think that Red John is patrick him self a kind of double personnality (Dissociative identity disorder) in sort of abusing of  transhypnos !!! think think 

Ok here's my prediction something a little different. Kirkland and pj team up in the hunt for rj. After bk admits he broke into janes place and tells him that his wife was also murdered by rj and wants to find him more then anything. Pj goes with and one by one they knock down the suspect list till its at the end of the season and everyone on the list is found innocent of being rj which leaves pj then believing bk is actually been rj all along but then at the same time bk then believes Jane to actually be red John and that's how they'll leave us till season 7 what a cliff hanger it would be

spoiler Alert! I think it's Patrick Jane for several reasons...

1. Red John has "disciples" and Jane can hypnotize and command people to do things very easily;
2. Red John knows whatever Jane is thinking and even knows his childhood memories that he never shared with anyone;
3. Jane could have developed a split personality due to issues in his past and his difficult childhood;
4. Either Jane unfortunately killed his own wife and daughter without realizing it due to a split personality OR he became just like the person that killed his wife and daughter from trying so hard to figure out who had done it, and the real killer got away (I'm still working on this one);
5. Jane knows more about Red John than anyone else;
6. If its anyone else on the list of 7 people, it just wouldn't be very interesting or enough of a twist;
7. Jane would never name himself as a suspect on his own list because he would never know he had a split personality.

Why Patrick Jane isn't Red John? Because the producer didn't want so... On his last interview on Inside tv,  Heller answer that question very cool:
Once again, you’re making moves that make me wonder if Patrick
Jane is Red John — after all, how else could he know that memory from
inside his head? But by saying Red John is definitely on the list, can we rule out the theory held by some fans that Jane is actually Red John?

Heller: I would say that definitively: Jane is not Red John.

I agree with Darkjane, theory #2905, that Patrick Jane is Red John.  I have watched
every episode starting with season one at least twenty times.  The writing on the
tile wall 'He is man/mar' is really 'He is mad'.  The letter d wasn't completed when
Red John wrote it in blood.  The episode where Jane was in the mental facility where he
was being released, was shown distorted by the camera.  The wall on the right side
of his room showed the red smiley face.  I hope there will also be a season 7 of The Mentalist.  I can not wait for season 5 to be released on DVD.

I think it is Patrick Jane. How else would RJ kill the girl who is  a happy memory from  Patrick's childhood? And to know the list of 7 people he shook hands with...whether he is under 24x7 surveillance or in his head.

First I didn't believed that Jane is RJ, because I remembered that Jane was sleeping all day, all night while RJ was killing the last victim (5x22) but then I watch it again and I saw that Jane isn't always in a cam view and when the cam is back on Jane he was sleeping on the other side. I know that he could go to the toilet, but why show that he change his side. Or it is just a mistake of director.