If you watch the keynote, you would see many of them. They put up a couple of slides near the end of the OS X and iOS5 presentations showing other new features and APIs that they were not able to go over in the limited time they had to present. I really don't feel like going through the video and finding them and then attaching it here but maybe someone else will.
I would also note that they do this at pretty much every OS presentation too for the past few years at least. There's a slide showing a bunch of new features in different text sizes that they did not get around to discussing.
I am not saying there are not other features. There are a lot of features already found. If you read my post carefully you'll even see I mentioned a few.
However, as I said, UI Customization is a big one. If it existed, it's VERY likely Apple would've talked about it. I mean, seriously: A camera button in the lockscreen? Do you think that gave more "WOW" in a Keynote than a hypothetical explanation of UI customization? They sure showed off wallpapers in the iOS 4 keynote.
So yes, I find it reasonable to assume that there will be no UI customization. As do many others. If you have any sort of concrete information otherwise - as you seemed so sure of yourself in the first reply you had -, then please spread it. I'd enjoy reading it, and as already said, I'd thank you and apologize to the MR community.
EDIT (to reply to your edit and the following post): Yes, I have read the other topic. And I have also seen the picture posted after you. See any UI customization in there?