I think Apple's taking their sweet time because they want to steal a bit of thunder from Microsoft in Nov. when the Kinect is released. They want people to take a look at the iPad come November again, it gives Apple something to shout about in my opinion.
I really don't care about printing with my iPad. I just want to enjoy multitasking like I do with my iPhone 4. Waiting till November is going to be very, very painful for me.