Aaron Saenz at SingularityHub wrote a really extensive piece of geolocation and the various solutions out there. 
http://singularityhub.com/2010/08/09/do-you-know-where-your-children-are-your-phone-does-geo-tracking-heats-up/
There was a lot in this article but I’d like to just comment on 2 of his key thoughts:
Where is all this geo-tracking headed? To some crazy places, let me tell you. It’s becoming pretty common to have your friends know where you are through social networks with geo-tagging capabilities.
I actually disagree with Aaron’s assertion that it’s becoming ‘pretty common’ to have your friends know where you are. It’s absolutely true that Facebook, Twitter, Foursquare, Flickr, and a whole host of other services allow you to geotag your location. But if I look at how my friends behave (primarily late-20’s and early-30’s technology early-adopters), I would have to say that a only tiny percentage of them actually do this routinely.
If I look at my Facebook news stream over the past week, I can identify at most 3 or 4 friends (out of a few hundred) that have posted their location every day out of all the various applications they can use to do so (Twitter, Foursquare, Gowalla, Yelp, Loopt, etc.) The more typical pattern I see is that someone joins one of these services and uses it heavily for a week or so, then quickly tapers off in their usage. Obviously there are exceptions to this example!
The key question is, why?
We think the answer is two-fold. Firstly: privacy. Most people don’t (yet) want all their friends to know where they are.
Secondly: lack of value. The ideal use case is serendipity – you happen to be just next door to your long-lost best friend from college but were unaware until your mobile social network alerted you to the fact. But the critical mass required for serendipity to routinely occur to the average user appears a long way off.
We think families are quite a different use case for both these reasons. The interpersonal bindings within a family tend to be stronger, the level of trust higher (as it should be!). Thus the privacy concerns are mitigated as long as the information stays within the family.
Families are also a better use case in terms of value. You see your family every day (or almost every day). The person you call most often on the phone to say “Where are you now?” is likely to be a spouse or family member. So providing that information in an easy, secure, and timely fashion makes real sense to our users.
The other thought I wanted to address was with respect to spouses. From the article:
But for spouses? Let’s look at BindTwo, the significant other version of ChildPulse and Whereoscope (same developer). BindTwo amounts to a sort of mate spying system. It can be used for good…or for evil. Jealous of your boyfriend? Now you can track him and call him if he goes somewhere you don’t like. I love the quote on their site that I think sums up the situation nicely: “BindTwo isn’t a creepy stalker app, it’s just a simple way to find your partner.” Oh, sure, totally.
I always thought it was a great tool for couples, but was prepared to believe that my innate bias as a developer was clouding my judgment. However when we launched, we were immediately contacted by couple after couple after couple, asking if they could use ChildPulse even though they had no kids. James and I are pretty devoted to getting feedback from our users, so we are having lengthy email conversations with many of them.
I have not yet heard from one jealous partner asking to spy on their girlfriend or boyfriend.
Every couple we’ve talked to has expressed a sincere desire to make meeting up easier, know when their partner’s coming home, and so on. It’s easy to make the joke as you do above, but I don’t think our users were lying to us.
If you lack trust in your relationship, these tools won’t solve that, and they’re not designed to. But if you have trust in your partner, our service seems to make people happier.
Wow this post is a lot longer than I’d initially planned 🙂 Let me sum up by saying I thought your article was excellent – it touched on many of the key issues that we think about on a daily basis.
Posted by Mick 
James
Mick
Whereoscope Blog 