Just in case you thought Google didn't already know enough about you, here is another reason to be paranoid. In all fairness isn't as invasive as it might seem, so let me explain a little about the search behemoths latest service.

Google Latitude, as the name almost implies, is a mobile (or computer) application that lets you share your exact real-time location with friends. Naturally it's an opt-in service and you can also disable it at any time, but it does have some uses.

For example, my friend Mark might invite me to come have a drink with him at a pub unknown to me, so all he has to do is launch Google Latitude on his mobile phone and his exact location will be revealed to me on my phone. Latitude will also give me the directions to get there. As Latitude relies on GPS as opposed to phone tower triangulation, it is accurate within metres.

A more useful scenario might involve search and rescue. If I was to go bush walking and find myself lost without any hope of finding my way back, I can reveal my location in a few seconds to anyone who cares to come rescue me.

And of course the service can be easily abused. If my partner wanted to see if I was really going into the office late at night she could enable the service on my phone and then track where I go in real-time in a web browser. It wouldn't surprise me if we start to hear reports of that sort of thing happening in the near future.

There is one small problem with the current mobile version which I discovered by mistake. I closed the app and then put my phone in my pocket, totally unaware that Google have introduced an extra option which requires user input before the app is really closed: "Do you want to continue sharing your location with friends? Yes or No?".

I discovered this a few hours later when I looked at my phone, and realised that I had inadvertently been sharing my location in real-time with a few of my friends all along. From a usability perspective, there should never be any input required after you have already selected 'exit' from the menu, especially on a mobile app that typically has high bandwidth costs if a service is kept running.

When not in use, Latitude will only show your friends the last location you were at when you last closed the app.

That aside it's a handy thing to have. I'm heading to my nieces Birthday party this weekend to be held at a location I'm not familiar with, but if my Brother fires up Latitude for a few seconds I will be shown the way. Pretty cool.