Why isn't my Tweet showing up?First, you need to "enable geotagging" on your profile page at http://twitter.com/ Second, you need make sure you use a Twitter application that supports adding location to Tweets. If you want to find a client that does support geolocation, look at Twitter applications used to generate Tweets the list on the left panel.
A few ideas: first, please read the above about adding location to your Tweets. We are not placing Tweets based on Twitter profile, but based on per Tweet geolocation.
What about privacy?We are only showing public Tweets (which is the default setting when you sign up at Twitter). Please remember that when you create a public Tweet anyone may be able see your Tweet content and location. Tweet with care.
How can I find specific Tweets?
You can search by location, username, keyword term using the "Search Filters" in the left hand pane.
Microsoft Fuselabs - Bing Twitter Map Project: