I have a long redstone wire in one direction (of course with repeaters). For example I have a piston 1000 blocks away and I press a button, so that the piston should do something - it will not do anything, because the chunk, where the piston is, is not loaded, I know this. But when I create the wire (not powered) and then go back an power it, only the wire within the loaded chunks power itself. But if I go along the wire, I will get to a point, where the wire changes from powered to not powered. And this point is exactly the last chunk that was loaded, when I powered the wire. I expected, that the wire updates itself when new chunks are loaded, but it only does, when I change a block beside where the wire changed its power.
I hope, I could explain it understandable. Please ask, if you have fourther questions.
See this video for more details: http://www.youtube.com/watch?v=e_MM97ifASw