If you guys haven't heard of it, some guy found a way to make "satalites" that can transfer redstone power across the map! I believe you can make 4 creations like this in each world, that's not much I know, but it can be really useful if your stuck on something or want the redstone to go really far away! And this doesn't even require a mod! Here's a video on it:
If you have any questions ask here since I've been playing with it for quite a while now
Yeah, its basic wireless redstone its been out for a while (the video itself is also pretty old)
There's definitely more than 4 channels (I dont remember the exact number, but its more than 10, as you can use glass panes and iron bars)
And for the "across the map" thing... its not true, the receiver needs to be in a loaded chunck, and the device wont work in multiplayer.
For more info, look for the wireless redstone discussion on this forum