Your exact location can not be discovered. There is no IP<->GPS translation. :p
Geo-location databases are becoming reasonably good, so it is becoming more common for people to be able to determine your general location from your IP address.
Is sounds like you have a more interesting question behind your original question. What's up?
I just don't like the idea of someone knowing where I am when I'm online. Even if it's my general location. It's like an invasion of privacy. If I had my way...I'd make it seem as if I was in a completely different country.