It may not be as bad as it looks on the surface, but Twitter is tracking your location when you upload an image -- something you could likely gather. However, given the social network's recent security issues, it could actually be as bad as it sounds. Today the company releases maps of where your images come from.
As I said, this is not the end of the world. Twitter is not broadcasting your location, but the fact is that, using geotagging, the company is keeping track of it. And your followers can as well.
According to Twitter's Miguel Rios, "a continuing curiosity is about the geographical shapes that surface in geotagged Tweets. The images we’re sharing here use all of the geo-tagged Tweets since 2009 — billions of them. (Every dot is a Tweet, and the color is the Tweet count)."
This is a feature that must be enabled on the service, but users should beware that Twitter is tracking it and that this information is subject to subpoena and would have to be handed over. The social service has posted hotspot maps on its Flickr page, though these only reveal where pictures were taken in general and nothing specific to users.
This is not new and is problematic with any service, not just Twitter. We are not alone on the internet and everyone tracks what we do, mostly for advertising purposes, this is only more confirmation.