I wonder if Raikou showing up in a dream is a hint at a future episode. I wouldn't put it past them and such an episode would be a good way to promote HeartGold and SoulSilver (yes yes I know! Anime=/=games, but does that mean one can't promote the other?). Because I haven't watched this episode but it seems like a 5 sec. "Yeah he exists, yay. move along now." type of thing which I hate (which made me a bit disappointed with how Regigigas was handled in the Shaymin/Giratina movie). So I'm hoping Raikou gets an episode soon and that this was a hint on what episode will deal with (Dawn being separated, getting into trouble/lost, Raikou finds her (maybe on his turf?), gets mad, Dawn gets scared, blah blah blah, Dawn earns Raikou's trust, reunites with Ash and Brock).