I am using Irrlicht Engine(branch-ogles with svn newest version 4389) in iPhone and select the opengl-es2 driver.
However, it seems not to support non-power-of-two image texture rendering. And I have successfully run an opengles2 example with non-power-of-two image rendering in iPhone.
So It may be that there is bug in COGLES2Driver or COGLES2Texture.