ok I aint read the entire convo but though I throw in my 2 cents worth.

The iPhone UI is so fluid because its so boring to look at, there I said it,

the reason I got rid of my iPhone 3GS was because every time I picked it up I was like, meh?? im board already. yes its smooth and slick, but if any company made a UI that bland and 'didn't' have it running to nicely they would be idiots, why??

- standard 480x320 resolution
- all icons are positioned in exactly the same location and are exactly the same in terms of size of colour depth
- there are no services running which might be using disk or network bandwidth

so its no wonder the iPhone OS is so slick, its because it aint gotta do nothing, plus have you tried using the latest 3.1 OS on a iPhone 3G?? OMG it is soooo sllooowwww and cumbersome to use, my in-law has a 3G and its the equivalent to using an old LG Viewty.

and on to multitasking! can a iPhone 3GS offer multitasking and keep the same responsiveness within the UI, the answer is NO IT CANT, I jailbroke my 3GS and enabled the multitasking plugin, it was not the same, very sluggish and very jittery - which reiterates my statement above, the iphone os is nice and slick because the iphone os is so damn boring to look at and doesn't do anything, except swipe 16 icons from left to right,

there. rant over