"Speaking with an insider at one of the UK’s largest chain of stores last month, we were told that during a meeting with Apple, the store was setting up for the iPhone 5 launch on 23rd September. Looks like Jobs is still fit enough to do a little shimmy and shake. KitGuru looks to tie down the real launch plans."
Source: http://www.kitguru.net/apple/iphone/jules/iphone-5-and-ipad-3-get-pushed-out-to-march-2012/
Take it with a grain of salt but I have found kitguru to be fairly reliable in the past