Yes, that's my point. Apple does reject apps that conflict with apple's core apps. I was unaware of competing email apps, because as I mentioned, I don't own an iPhone just yet. I used too, and I'll probably get an IP5 or an IP4 (I mentioned this in other threads so I'll not hijack this thread with my tale of woe).
With the iPhone, apple typically rejects apps that compete directly with their stock apps.
I saw an article a PC World today about something like this. Apple doesn't care about controlling the market. Apple cares about making money. Do you think that Chick-fil-A's owners care that McDonald's has sold bajillions and bajillions of hamburgers? Do you think the BMW people care about Ford's sales?
There are many apps that integrate into iOS just like stock apps. I think Apple is just careful of exactly what apps they will let be integrated.
"Integrated" usually means they can automatically take the place of default apps.
In other words, if you click a button or link to launch the browser or map, or take a picture, or send an email, or choose a photo to send, those stock code sections can be replaced by third party ones.
Apple doesn't allow such integration.
Meizu (one of the better Chinese iPhone knockoff manufacturers) has the M9 which is just as smooth as the iPhone using Android.
Meizu M9
http://www.youtube.com/watch?v=T0Zz-BhYVpw
From PlayStation Androids to 3D/glass free Androids to the Atrix 4G, I don't see the next iPhone being the phone for this year. The best phone of this year will likely come from Android. This is their time. Their invasion.