Tor is the short for The Onion Router and the services it brings to users are anonymous Web surfing by using multiple servers and routing traffic randomly through them resulting into masking user’s true IP address.
If you want to use this feature at the moment you must have Firefox with Torbutton extension installed on it.
For the future the developers plan to remove Torbutton from Firefox and create a new Tor browser which will have this feature. One of the reasons of this is that it takes a lot of time to fix bugs within the addon.
Personaly I find this feauture interesting but I wouldn’t like to change my web browser to a new one.
sources: https://blog.torproject.org/blog/toggle-or-not-toggle-end-torbutton , http://news.yahoo.com/s/pcworld/20110505/tc_pcworld/asfirefoxrevsitsenginesanewbrowserisplanned , http://www.engadget.com/2011/05/07/tor-to-fork-firefox-for-simplified-anonymous-browsing-doesnt-t/