After your Rook goes to e1 and your Knight goes to f1 (ready to go to h2 and then possibly g4), your dark squared Bishop easily participates in the kingside attack (that is the point of this opening after all...). Here, take a look at these two videos to understand more about he opening:
http://www.viddler.com/explore/Fuzz/videos/23/
http://www.viddler.com/explore/Fuzz/videos/25/
I'm pretty new to chess, and I like playing the King's Indian Attack. It has some definate weaknessess, notably the trapped black square bishop. I have been trying to deviate slightly where I move my Bishop from c1 to either d2 or e3 on the third move, and then continuing with the regular formation. This move gives the bishop a much greater range, but substantially weakens the left side, though it is possible to compensate by altering the far left pawn structure, and using the queen and reinforce it. I know better than to trust myself to deviate from established systems created by people a lot better than me, so I'm just interested in hearing peoples opinions, if they have a better variant, or if I should just stick to the regular plan.