Gmail grows day by day and adding more features in Labs and make those features live that which are gaining the hearts of users. On April 8th 2009 night Gmail has released a new product in labs called "Sender Time Zone". This is a nice feature. Using this feature you can find what time in your contacts country.
Don't get confused. For example you have friends or clients world wide. For example you have received an important mail from client or friend. You would like to discuss about that issue immediately to him or her and wants get it resolved. If it is early morning to your client or friend, then it's so bad to disturb them in a deep sleep. So using this feature just simply have a look on time zone (as shown in the image) and then call him if it's the right time or else wait for few hours. (click on the Image to enlarge)
If you have all local friends then it won't much use for you, because yours and their time zone is same. For professionals and Global consultants have found this feature very useful who have global network and also interacting with them often.
But here is a problem again. If you are in India and your system has set to US timings then it may show your time wrong. So it would be better to set your system according to your time zone. Of course most of the people will set their pc time zone as per their time zone only, however i just want to make you aware of this.