HDMI has a feature called CEC which can control inputs, volume, channels, basically everything a normal remote can, but over the existing cable and connection. https://en.wikipedia.org/wiki/HDMI#CEC

Is there a reason I haven't seen this used for DVD players and game consoles? (Or am I just living under a rock?)

When I turn on my PS3 my Samsung TV automagically turns on and switches to the appropriate input.

My Toshiba TV and my Onkyo receiver both support it. It's not a cost/licensing issue since it's built into HDMI and Pulse-Eight makes a USB CEC HDMI passthrough adapter and provides a libCEC library: http://www.pulse-eight.com/store/products/104-usb-hdmi-cec-a...

PS3 supports it. Although not when the youtube app is running for some reason. When I turn my TV on, the PS3 starts automatically and I can use the remote to navigate menus and Netflix.

Only in CECH-2000 model and later, though.

http://manuals.playstation.net/document/en/ps3/current/setti...

Not all TVs support CEC or have it turned on by default.

My bluray player (a Sony from a couple years ago) does this perfectly fine with my Samgsung TV. So, some devices use it.

Works great between my Samsung HDTV and Panasonic BluRay player, both 3 years old. Only have to use one remote. :-)

Wii U gamepad has a TV button that turns the touchscreen into a remote control for my TV.

This is not the same creature, though -- The Wii U gamepad has an infrared transmitter that allows it to act as a universal remote.

AFAIK, the PS3 is the only current generation console to implement CEC.

Not sure, but XBMC supports it.

It's worth noting that each consumer electronic manufacturer has its own name for CEC, rather than using the generic term. This, despite good compatibility between manufacturers' implementations.

From the Wikipedia page linked by the parent:

Trade names for CEC are Anynet+ (Samsung), Aquos Link (Sharp), BRAVIA Link and BRAVIA Sync (Sony), HDMI-CEC (Hitachi), E-link (AOC), Kuro Link (Pioneer), CE-Link and Regza Link (Toshiba), RIHD (Remote Interactive over HDMI) (Onkyo), RuncoLink (Runco International), SimpLink (LG), T-Link (ITT), HDAVI Control, EZ-Sync, VIERA Link (Panasonic), EasyLink (Philips), and NetCommand for HDMI (Mitsubishi).

Clearly, they needed to specify something catchier than CEC in the HDMI spec!

So THAT'S what my Sony BR player is doing when the display keeps switching away from AppleTV! Drives me nuts...

Apparently, CEC-less cables are available: http://www.pulse-eight.com/store/products/110-cec-less-hdmi-... (25cm long)

Thank you!