I tried, but it was before iPhone had any kind of push notifications, live in a low population area, not a lot of my friends are early-adopter social tech types

I tried, but it was before iPhone had any kind of push notifications, live in a low population area, not a lot of my friends are early-adopter social tech types, and I'm too old to want to hang out with random people I saw on Loopt -- so, it didn't work for me. I'd be willing to give it another try. Interestingly, in the meantime, there was a lot of foursquare adoption among friends and in the area -- enough to get network effect benefit. I don't think many of my friends have heard of Loopt.