Gmail had added another great innovative feature, email signatures can now contain the location where the email was sent from. This is easily activated in labs and looks like the pic below:
It simply works by using your public IP address which means it may not be accurate all of the time. On the blog post, they mention that your browser of choice should have the latest version of Gears to ensure accuracy. This is an excellent feature that I'll be definitely activating for my emails. Gmail is definitely the fastest evolving email out there, and is catching up with the two biggies, Hotmail and Yahoo mail.