I've tried the v11 again but now on another iPhone4 and an iPad3. In project->options I set the Resolution to 768x1024 and then on the iPad3 my GLB app runs in 768x1024 mode instead of 1536x2048, which is a correct improvement from v10 to v11.
However, on the iPhone4 my GLB app now still runs in 320x480 mode, I can't figure out why. I've even uninstalled both GLBasic v10 and v11, and then only re-installed v11.
Here's my new info:
GLBasic v11.261
libpng-gf.a => 14-dec-2012
libGLBasiciPhone-egl.a => 14-dec-2012