the easy, but disappointing, answer is this: your flash swf will not show up on either the iphone nor the ipad no matter what, as those apple devices do not support flash.
your alternate content* should show up and scale normally on those apple devices using Mobile Safari, or any of the other browsers available for iphone( iCab, Mercury, Skyfire, etc
so whetehr the item is centered, or positioned left 300px, it will remain scaled
and positioned proportionally on the iphone and pad.
** you should always have 'alternate content' embedded along with the swf for any cases where the swf will not show up. use swfobject2 for best results. you can generate the code here:
http://www.bobbyvandersluis.com/swfobject/generator/index.html