ML1888, That's because you are new. It goes into an approval area until they see enough that you are not a troll or spam.
As for you, ClockworkPrince, I don't see why that would be happening to you..Maybe because you still have a very low post count. I think admin has it where after a certain number of approve posts, you won't have to wait. This I am not sure about but it seems like a good reason..