Continuing in the theme of where is your audience.. for knowing where you are the concern is whom you allow to know what level of resolution.
Now I don’t always consistently update my location. Just randomly when the mood hits me. Or when I want to publish it. Sometimes I am other places and leave it on a certain location on purpose. Here is how I handle my geo location information. I start with my iPhone 3GS that has full GPS. On the iPhone I normally use the http://www.brightkite.com/ application because it makes updating my location stream one touch. Next if I have friends that I want to see my exact real location I can give them permissions from Brightkite as long as they have a Brightkite account.
The world at large I would rather just see city general location information. This shows up on my http://www.georgestarcher.com blog and in my twitter location field on my twitter profile. So I let Brightkite and Fireeagle cross control each other. Then I use the superb privacy per application link controls from http://fireeagle.yahoo.net/ to send only city level information to EagleTweet for twitter updating and my blog via a widget. One of the best things about Fireeagle is it requires you to regularly keep your account active for sharing. Think of it as a deadman’s switch. If I fail to renew my authorization it stops all sharing to all apps tied to it. I have my renewal set to require it monthly.
Below is a diagram of the information path.