With .iso entry boot support does this actually add a working entry for an .iso file to the Windows bootloader or does it use grub2 loopback/grub legacy map to accomplish it?
It creates a modified loopback device in GRUB, but you won't see it because it injects the code directly into the bootloader so for all intents and purposes, you're loading it directly from the boot menu.
I plan on giving it a try this weekend. You're right, no big deal of course. I was just curious if it was possible if the Windows bootloader could load iso files like it can vhds.
Loopback doesn't work with all ISOs unfortunately due to kernels that wipe out the virtual devices grub uses. For example you can't install Windows on a machine using an iso.