There is no stopping Gmail Labs from releasing better products. Be it taking your Gmail offline with Gears or putting location to it, presently the Labs will released Sender Time Zone. The features enables users to know if the contacts in their list be up or asleep and this is based on the time zones in the emails they sent. This is pretty useful to determine how quickly you might get a response to your email. You can view details to learn the time (senders) they sent the mail and the current time at their location. So if you see a green phone symbol next to your contacts name know that they are most probably awake.
