The main issue with running Macosx on the 360 is the video drivers. As most of the pc osx users have noticed, there is a great lack of avaible drivers for osx for their existing video cards. Now while there are several projects out there right now to get the cards working with both CoreImage and....and...what ever the other one is, I forgot, its still going to be a long as way to get it all going smothly.
Also, the verson of osx we are screwing with is designed for the x86 processor, not the powerpc. To my knowlage, I dont belive that anyone has ever removed use of the TPM checks on a ppc version of osx for reasons beign, there are not any clone macs out there. A whole new version of osx would need to be hacked.
Here is a list of what needs to be done
*Video Drivers
*Input devices
*TPM checks
*sound drivers
*Disk usage
*Boot proceadure
*network interface
*and xbox360 security checks for unsigned code.
Thats all I can think off the top of my head, and I know theres alot more. Pretty much, I think its hopeless