Due to a change in Web of Trust's access to their API, the "Web of Trust" plugin for POP Peeper is no longer returning valid results. For some URLs/domains, you may still see valid results due to caching, but you will see an "unknown" result for any domains that POP Peeper had not previously checked with wot.
For multiple reasons, the decision has been made to officially remove Web of Trust integration as of v5.1.
The plugin itself, even without WOT integration, still has value as allowing you to whitelist URLs. Instead of simply removing this plugin from v5.1, this particular aspect of the plugin will be enhanced.
Going forward, I am considering an alternative solution, which is Google's Safe Browsing API.
I am open to discussing this -- feel free to start or join a discussion in the POP Peeper forum or contact me directly.