The Gmail Team has introduced yet another useful feature in their Labs. Now you can append your current location (that is the city`s name you are in) to the email`s signature. For this to work properly you need to have the latest verion of google gears installed with the support for the Location API of Google Gears. In order to turn on Location in Signature, go to the Labs tab under your GMail settings page and then go to your signature preferences and check the box next to "Append your location to the signature."
Now this is how this entire feature works. The Location API in Google Gears uses your public IP address to determine your location, so the detection may not always be that accurate. As the gmail blog puts in an example that if you're at Heathrow airport, IP detection may put you in Germany. If you want more accurate location detection, make sure your browser has a version of Gears that supports the location module. That way, Gears can make use of wi-fi access point signals to recognize your actual location.
In case you dont want to reveal your location in your mail signature for a particular email just delete the Location automatically appended by GMail (which is in plain text format). You can also disable this option by going to the signature preferences. You can also read our story on Accessing GMail Offline via Google Gears.