Peer Block is a new version (aka a "fork") of the popular Peer Guardian 2 software. It blocks "known bad" computers from accessing yours, for example governments and corporations. Peer Block maintains the functionality of the original Peer Guardian 2 program, but includes fixes for various Windows Vista / Windows 7 issues that remain unaddressed in PG2.
At one point, Open Hub analyzed source code for this project based on code location(s) available at that time. Since then, the code locations have been removed.