Well, this is kind of insulting to YC and it's longest running posterchild, Loopt - http://www.loopt.com/ Can't believe no one here mentioned it.
I think what sets this apart from sites like Loopt, Gowalla and Foursquare is that those sites are oriented towards the social networking aspect of geolocation. Those sites are community based where as this seems more like a nice little utility app for giving someone directions. The real time tracking and simplicity is what makes this unique I think. Not sure where these guys are going to take this but I would urge t…
Yes, I agree Loopt and the sort are more social/community oriented these days. But, back in the day before Foursquare, Gowalla and even the iPhone (and Android) were alive, Loopt did this first and did it rather gosh darn well.
That aside, the app is pretty neat. It'd be nice to have an embeddable version in the future so let's say you arrive at a restaurant or whatever, and your location could be broadcasted or narrowcasted to the rest of the group. I could see this working with maybe a facebook group or whatever.