If I am not mistaken you can only have 16 icons on screen and that too only on 9 virtual screens. Now do the match and you will have 144 app's and webclips.
That's a lot of app's and webclips on a mobile device. Is apple trying to stop people from putting more or do they think that is a good number and people will not need more than that.
They could always make the screen move vertically but after seeing this UI change can you imagine going horizontally to the 3rd screen and then going down again vertically that seems painful and I think apple will not make such a UI change.
So 144 seems a good number to project.
Looking at all the things they are doing on the iphone the last thing they might want to do is make it complicated. So they will stick with the UI and limit people to 144 app's.
They could always put a search feature like they have on their site which brings up the programs. But even that makes it complicated and I think they will not do that.
So 144 is the magic number, i have around 60 programs on m