This is one of the best blog posts on LBS I've read so far. Thank you!
I tested Placepop, 4square and Gowalla in Europe (which is where I live) and while 4square and Gowalla have far more features, I found Placepop to be the most acurate in terms of finding my location. I guess if you are an avid gamer, you will like the Gowalla interface the most, but if you are like me and just want to share your current location with your friends, then Placepop wins. One of my hobbies is a small restaurant blog at http://www.essenbildet.de and apps like Placepop are great for letting my readers know where I am eating at the moment including an up to date picture and a short comment. Obviously it would be great if they had an API which I could ty back into my blog, but I am sure they are working on all those features.