I had to do the same thing. I set some values early in my code to calculate a multiplier factor using the following:
local dWidth = display.viewableContentWidth
local dHeight = display.viewableContentHeight
local dWFactor = dWidth/320
local dHFactor = dHeight/480
Obviously I set my default to be the iPhone and then multiplied by the factor each time I needed a current value. It works in the simulator & I havent tried it in the real device yet. (Still playing!)
The only problem I ran into is that the values for some of the devices are fractions such as 1.6666666 for the Nexus One Height factor. I had to round down for some seamless effects using math.floor() as appropriate. [import]uid: 102145 topic_id: 19482 reply_id: 75153[/import]