Nokia has confirmed the availability of Symbian Belle for Nokia E6, but you should expect the updates in 4 Qtr of 2011.
Belle is the code name for Symbian's OS latest version. It offers refreshed UI with better icons and fonts, appealing visuals and animations and a portrait-oriented full QWERTY keyboard. Belle also comes with great performance improvements which means its more responsive to your input and save battery life.
Symbian belle features more customizations, new widgets and apps and NFC support.