Is Twitter a security risk?

I use Twitter, it’s a fun tool to keep half an eye out on some of my friends and other interesting people are doing right now. I think it’s a pretty decent communication tool. But like many tools it’s easy to over communicate. Some of the people I follow have started using Twitter mashup Brightkite and are using it to send pictures with location information to Twitter. I trust that folks like Mediaphyter are savvy enough to carefully regulate their information, but I have to wonder if the avera