plsync is a replacement for rsync, written entirely in Perl. Its features are or will be (if not yet implemented)

• efficient usage of network bandwidth
• efficient usage of memory
• clear reports on what has been done after a plsync run (and what has failed)
• Software hooks so certain files may be treated specially
• Transfer data from a remote host to another remote host directly

Right now, plsync is deep in a development phase and the current version will undergo fundamental changes in the future.