I see that these days, computer screen pretty much have 16:9 ratio, you know, those 1900 x 1080 resolution and what not. Mobile devices also have widescreen for landscape perspective. But there are various aspect ratio for many devices. iPhone 4 is 640�960 and the iPhone 5 is 640�1136. All these are different aspect ratio. Ashley has already posted a tutorial regarding this matter at scirra.com/tutorials/73/supporting-multiple-screen-sizes
I am curious What aspect ratio do you usually use for your game? And I also would like to know what is the most famous aspect ratio right now, for mobile devices (tablet included) ?