Every six months or so somebody proposes a new system where people can leave messages in cyberspace that are tagged to specific places or co-ordinates. It always sounds enticing at first, like you could walk past a restaurant and see all the messages left by people who have eaten there before, letting you know whether it's worth eating there or not. Two words for you: Third Voice. This was a dot com-era browser "enhancement" that let you view messages that other people had left when you visited a web page. The idea was to open things up to "interactivity" and let people share their thoughts and comments about sites, but you can guess what happened—like any unmoderated bulletin board on the Internet, the system was overrun with spam and flame wars. What Siemens is proposing is a system of "electronic post-its" for cellphone users, basically a way for someone to leave an SMS text message that is tagged to a specific place and is only transmitted when someone walks through that location. Siemens claims this won't be a problem because there "will be ways to accept and reject messages," but if the system isn't closed or restricted in some way it's just going to be a brand new way to annoy us.