Basically if a plug-in allows you to show "Content" to these "Countries" it's more then likely using this plug-in as a feature. So yes plug-ins like banners can use this to show Canadians geo based content. like "Canadian singles find a date now!" to only Canadians.

Dear members,

Recently I spent much time investigating this issue of IP Geo-location for AdSense, but didn't manage to find a clear answer.

I did this after I've seen that OxWalls running this plugin have a much higher CPC than my other websites, that are using normal Adsense banners. It seems that this plugin is indeed able to target better than without.

On the other hand, Google says that IP is being determined automatically and no additional plugins are required. In a way it's true, because you can see detailed analysis per country in the Adsense statistics.

I'm planning to try converting this Oxwall plugin for a php website, although I'm not sure if the effort worth it, as the info is very contradicting.

Please let me know if someone knows about this issue.
Cheers.