> This usually means spam, but it can also mean if a node is acting in bad faith (ie, it's revealed that AppleBook is selling non-local user data), or if they'r

> This usually means spam, but it can also mean if a node is acting in bad faith (ie, it's revealed that AppleBook is selling non-local user data), or if they're abusing the protocol. That can act as a certain type of social "shunning" on a node-to-node basis. There are interesting, open theoretical computer science questions that determine how effective such an approach can be, and how susceptible it is to attack. Without a theoretical understanding of how your reputation system works, how do you propose to solve the spam and "evil" problem? In other words, if we invest heavily (time and money) in this, how do we know that it won't eventually be overrun by spam after being mastered by a clever (or lucky) hacker? If you haven't already, you should check out: http://en.wikipedia.org/wiki/Byzantine_fault_tolerance http://en.wikipedia.org/wiki/Byzantine_fault_tolerance -- the Byzantine agreement problem, which deals with a distributed system agreeing on a global decision (substitute "failure" with "evil"). These are not trivial problems to solve, and if you intend on scaling, I hope you have good solutions to them. Distributed systems are notoriously hard to understand and maintain; it sounds very nice to propose a new distributed system, but it's hard for a hacker to accept your solution until I have some theoretical assurance about its security model.