According to a report from the crew over at Nokia Tips the next build of Symbian, Carla is being tested on the Nokia N8. Which I am praying to be true because previous reports of Symbian Carla only had Carla running on 1GHz and faster processors. This means that the N8, E7, C6-01, and E6 would not get the Carla update.
Here is the bottom line from the Nokia Tips article:
Sources inside Nokia Brazil have confirmed that test builds of the next Symbian iteration, namely Carla, are running on QA Nokia N8′s.
This report of Carla in testing gets me thinking perhaps it will get released earlier than the rumored release date of 4Qtr of 2012/1st Qtr of 2013.