Open Invite collaborative blogs succeed on the basis that the community acts to weed out trolls, spammers and other troublemakers.
A more robust distributed approach is Akismet, which uses a similar approach to LinkSleeve but uses API keys to assign trust to nodes and also has wider distribution as a result of being bundled with the 2.0 release of WordPress.
CAN-SPAM Act of 2003 | Anti-Spam Research Group | Email spam | Spam in blogs | Spam fritter | Messaging spam | Forum spam | Anti-spam techniques |