I have a Panasonic TV, a Comcast cable box and a Denon receiver. Everything - the Wii U, the Comcast cable TV signal, and our PS3 - run through the Denon receiver before reaching the Panasonic TV. The Denon remote controls the surround volume, but the Comcast remote changes the channel. Currently, Wii U cannot control stereo receivers (i.e. my Denon). Apparently, there are others in my situation.
Hopefully NOA Jane or other NOA Support Staff see this and aim to tackle it for a future firmware update, as it would be truly awesome to have only one remote. My parents are finally getting a new entertain set-up (after the same TV for 28 years 
!), and we might get them a Wii U, but the set-up they are eyeing would yield the same predicament I am in now.
Thanks to Nintendo for this cool feature, but hopefully it will be improved as well.
***Edited to remove link as it contained the sharing of friend codes.***
Message was edited by: NOA_TECH_MIKA