I have a Sharp 835U 3D TV, Comcast Hi-Def box (Motorola DCH3200) Panasonic BDT210 Blu-Ray player, and a PS3 hooked to a Sony CT150 soundbar; all via HDMI.
Here is component interaction that I have noticed so far:
The TV controls the sound level, muting, and power off/on of the sound bar.
I keep the Comcast hi-def box powered on all the time and normally have the soundbar input selection set to CATV/Cable. When I insert a disc in the Panasonic Blu-Ray player, the sound bar automatically switches the input from the Comcast box to the player (BD). However, when I eject the disc or power off the player, the input does not switch back to the Comcast box.
When I insert a disc into the PS3, I have to manually switch the input on the soundbar.
I have not yet tried keeping the Comcast box powered off to see if the soundbar input selection switches automatically to the one component that is powered on.