Symbian used to be the most widely used OS on mobiles, it still has the biggest share in mobile os but when it comes to smartphones, symbian is not just upto the mark.
To meet the demands of next generation and smartphone Nokia introduced Symbian^3.
Symbian^3 was announced on 15 February 2010. The Symbian^3 release introduced new features like a new 2D and 3D graphics architecture, UI improvements, and support for external displays via HDMI. It has single tap menus and up to three customizable homescreens (more like android).
Six smartphones with the Symbian^3 operating system have been released so far; the Nokia N8, Nokia C6-01, Nokia E7-00, Nokia C7-00, Nokia E6, and Nokia X7. Nokia N8 has been a big hit, more because of its camera rather then its Operating System.