Yesterday, I was disturbed to learn of a new practice in the fourth grade. In Charlie's class, the teacher gives "rabbits" to good, quiet little boys and girls, which can be traded in for "class recess time". We, of course, are concerned by reward mechanisms like this, which are 
used to foster devisiveness and competition among students.
It's not a coincidence that coercive discipline programs rely to a large extent on getting compliance by slathering on praise. A typical example is the elementary school teacher who is taught to say, "I like the way Cecilia is sitting so nice and quiet and ready to work." I have multiple objections to this practice.
Why?
First, the teacher hasn't done Cecilia any favors. You can imagine some of the other kids coming up to her after class: "Miss 'nice and quiet' dork!"
Second, the teacher has just turned a learning experience into a quest for triumph. She has introduced competition into the classroom. It's now a contest to see who is the nicest, quietest child—and the rest of you just lost.
Third, this is a fundamentally fraudulent interaction. The teacher is pretending to speak to Cecilia, but she's really using Cecilia to manipulate the behavior of the other people in the room—and that's simply not a nice way to deal with human beings.
Fourth, and possibly most important, I ask you to reflect on what is the most important word in that expression. I believe it's "I". Even if such a practice "works," it has worked only to get Cecilia and the other people watching to become concerned about what "I "demand, regardless of what reasons "I" may or may not have for asking her to do something. Cecilia is not helped one iota to reflect on how her experience affects other people in the room or what kind of person she wants to be.
On that point, I like to think about the questions that kids are encouraged to ask in different kinds of classrooms. In one dominated by consequences, kids are led to think, "What do they want me to do, and what will happen to me if I don't do it?" In a reward-oriented classroom, including one that is characterized by praise, kids are led to ask, "What do they want me to do, and what will I get for doing it?" Notice how fundamentally similar those two questions are and how radically different either one is from the questions, "What kind of person do I want to be?" or "What kind of classroom do we want to have?"
I suggested to Charlie that the students should get together and put all of their rabbits in a jar, or maybe in a "zoo", so that it's clear that they're shared by the whole class. He has a hard time understanding our concerns -- he's just focused on the idea of more recess as a good things. Its a particularly insidious form of competition because the reward is shared -- the competition is only for the tokens.
I was excited to see that some folks are building learning management system components for tikiwiki. I like tikiwiki more and more as I use it, although some of the modules need work. If I had time to figure out how they work, I'd contribute. So far, I've found the system to be inscrutable. One of these days...