So Latitude had that big breakdown a few weeks back and was not updating or locating friends.  The issue I'm finding now is that it appears to update only after an hour.  For example, I'll open the app on my IPhone 3GS and Latitude will have found a friend 20 minutes prior.  The app will not update locations for another 40mins or near the 60mins mark, even when I pull down to refresh.  I am the only one with an IPhone, my friends are using Droids.