i have the same problem running wp behind a reverse proxy (just 1 unique IP visitor). REMOTE_ADDR is set to IP address of reverse proxy server, while HTTP_X_FORWARDED_FOR is set to client IP address. Switching contents of $long_ip[0] and $long_ip[1] in _get_ip2long_remote_ip() would show numbers of unique visitors correctly but might be a dirty solution.
btw, camu thx for that great plugin, looking forward for IP anonymization 🙂
