US is mostly covered by 4G/LTE, Europe/UK operators are also in testing phase. Many big operators from Middle East, Africa, Australia are planning to start 4G by 2012 end. I am sure by 2012 end we (in India) could have some significant development in 4G.I doubt any existing operators could launch 4G due to their investment in 3G, but Reliance (RIL) could surely start service in 4G by 2012 end.