swa66 - 6:49 pm on Nov 3, 2007 (gmt 0)

Don't forget that no matter how accurate the database (none ae very accurate), you will still have errors with people who are on a a trip abroad, with companies surpassing country boundaries and their internal network having just a few exits in just a few countries. And the I didn't even talk about TOR or open proxies used to evade geo-targeting.

In general I don't think it works well enough to be of much use beyond targeting advertising to audiences (where it's no big deal if you miss a few).
If you want to make sure nobody from country X can access your site, I doubt it'll work.
If you want to be sure people of country X cannot buy your stuff (cause you don't want to ship there or have too much trouble with getting paid properly), ask the shipping address and if you don't like it, quit there.

Don't forget the Internet is what it is in part because of the surpassing of obsolete country borders. All geo-targeting does is building in those borders again, and it'll backfire as the adopters of the Internet will not agree with you in the long run.