My Original reply follows bellow. It was valid at the time I posted it, but Apple does not allow the usage of UIGetScreenImage anymore. To the best of my knowledge after the launch of iOS4 there's no alternative how to render layers with 3D transformations + your app will be rejected if you use UIGetScreenImage
From the iPhone developer docs on renderInContext :
Additionally, layers that use 3D
transforms are not rendered, nor are
layers that specify backgroundFilters,
filters, compositingFilter, or a mask
values.
So renderInContext is not the function you need to use to render a layer that has a 3D transformation applied.
Best you can do is call : UIGetScreenImage, which basically will give you a screenshot and you can then extract the image out of this screenshot.