10m can be problematic for Digital (HDMI) and Analogue (SCART) if you don't use a decent quality cable.
HDMI at 10m can be affected by the resolution of the signal your going to be running from your Source so ensure any cable you install is compatible with every resolution you plan to use.
If you only have a single HDMI Input on your Display and want to hook multiple HDMI equipped sources to the Display then some sort of switch is required - you don't need to spend a fortune on a decent switch; see http://www.octavainc.com/
Keep in mind you need to ensure the signal your Source is Outputting over HDMI is compatible with the HDMI Input on your Display.
HDMI cables are pretty much always Plug to Plug and your Source and Display will have HDMI Sockets.
PS The SKY HD box has Analogue (3RCA 'Component') and Digital (HDMI) HD capable video output sockets - if your Display has compatible Analogue (3RCA 'Component') Inputs you could use that input for SKY HD and not require an HDMI switch unless you add additional HDMI equipped Sources.
Now I have decided to run to a location which will require 12 metre cables - can anyone who has experience of this distance recommend a good quality cable(s) to suit? I will need to connect Sky+, dvd, video for the moment, but need to future proof myself for sky HD and the PS3 when it arrives!
Why does there seem to be few suppliers of scart to scart leads? Are these frowned upon, poor quality or what? Some equipment will have to be connected this way!