What's new in iRobot Roomba Series 500 Vaccum Robot?

1.Improved cleaning performance
2.Improved navigation
(1) Virtual wall with infrared tower provides it the ability to clean a room exactly than go to the next room.
(2) Soft touch bumpers to slow down velocity when approaching a barrier.
(3) Anti-tangle let Roomba to operate on different surface even on the carpet.
(4) Home based for recharging and docking
3.Easier to use and upgrade with modular design
4.Voice demostration
5.Wireless command center for more conveniently control

Link:http://www.irobot.com/sp.cfm?pageid=334

Virtual wall for room to room cleaning:
http://www.irobot.com/video/roomba500_tech/Lighthouse_tech.html