Here is an explaination stolen from Grayfal
"This is the OP's explanation from 2Peas:
You could pick your own theme (favorite ride, favorite character, most memorable Disney experience, favorite place to stay, etc)....
Here are some 'rules':
Each of us will buy a book that we want our CJ in (6x6, 8x8, 6 1/2 X 10 or 5x7 are preferred for easier mailing). You will come up with a Disney theme for your book--it is TOTALLY up to you but be creative! You will create the first page with an introduction as well as some sort of sign-in for your book. Some people do a page where everyone can sign in with information about themselves; I've seen other variations. Do whatever you want. You will then send your journal to the next person on the list, who will do a page according to your theme. Each month you will receive a journal to add an entry to, and at the end of a year you will receive your book back, full of the experiences and wisdom of the people in our CJ group.
This is a YEAR LONG commitment, please do not sign up if you are not going to be able to make that commitment. You are committing to completing a page and sending it out by a specific deadline each month. You will be responsible for postage each month. If these are not commitments you are able to make, PLEASE do not sign up for this circle journal group! We are trusting you with little bits of ourselves!
The 
It was a year long CJ...and this month (Oct.) marks the 1 year....but so far I've only recieved about 1/2 of them. Anyhow...hopefully it'll get moving and finish soon. But I would like to join in another one. Maybe if anyone could give me some pointers on hosting I'll go for it. 
