Originally Posted by medion
IE 9 mobile is being adapted to the ARMv7 instruction set. You'd need a CPU that can run that. The Zune doesn't have it.
Also, every device set to run IE9 mobile has 512MB of RAM or more. I'm sure it could run on a device with 256MB, given how WP7 and the Zune HD don't run much in the background. However, the Zune HD has only 128MB of RAM. It's already RAM starved. That's why it's running a stripped down version of IE6 Mobile (yup, it's not even as capable as what's on WP6.5).
It cannot be technically done. It won't be done.
256 MB is the minimum requirement for WP7. This is the time I wish the Zune had more RAM. Also not all WP7 devices has 512 MB. Some have 256, others 448(like some HTC phones) others have 512(Focus and others) and I believe a coupe has 576.