By default, TweetCaster only uses your GPS signal for the Nearby function, which finds Twitter uses near you. We do not automatically capture or display any GPS information internally at Handmark or externally to the Twitter community.
If you do wish to display your location in your tweet, tap the location icon on the New Tweet screen to enable geotagging. When location is enabled in this way, TweetCaster will include your current location with your tweet.
Please note that in order to enable location in TweetCaster, the "Add a location to your tweets" setting must be enabled in your Twitter account settings.