Is it possible to block certain IPs based on their geolocation using this hack?

No, this is wrong.

This program is based on IP address which comes "without network load cost" from the HTTP $_SERVER['REMOTE_ADDR'] global PHP var.

Basically, the server simply takes the REMOTE_ADDR (IP address) and queries a file on the same server (can download file for free) and returns country information.

This is a great feature for many forums that would like to display different content to the user based on country.

Yes, you can easily do this, but you need to write the extra code yourself.

Yes, it does. Basically, with a bit of writing code, you can do "just about anything" based on Country (or even City).

For many users, it might be easier just to install this PHP extension (since this mod is not supported anymore):

http://us3.php.net/manual/en/book.geoip.php

Ah, we found it was easier to install Apache2 mod_geoip. A plugin for this is not really necessary, FYI. So, I recommend mod_geoip for this because it is easy to install and runs great.

We have integrated GeoIP into vBulletin very easily using mod_geoip.

Details on upgrading mod_geoip here

What we have done so far, is use mod_geoip for geo-targetting.

In addition, we made a simple change to the navbar template to say:

Welcome from Country_Name, User_Name

instead of the standard, Welcome, User_Name

Details on vB navbar feature here.

Has anyone ported this to vb4 yet?

Does this work with vbulletin 4.1.11? Does it work with Amazon Associates?