http://www.autoblog.com/2012/11/14/bmw-announces-plans-for-new-retro-motorcycle/ could be interesting
I may be a cynic but I bet this is a way of selling the 'old' twin cam engines whilst they ramp up production of the new water cooled engine to the R and RT models. So RTs get the WC model in 2014, R in 2015. I'm waiting for the reviews of the new WC engine, I have a feeling that it will be a cracker!