Also, I realized that you might be wanting to use a boot partition so that you can eventually put an ext2 filesystem on it and make it like a normal distribution's "/boot" partition.
Is that what you're thinking of doing?
My main interest in using a GTP partition table is so that I can boot from a Western Digital 3TB HDD with Advanced Formatting.
I guess that if the stage1 or uBoot loaders are unable to handle the 3TB HHDs with their difference between logical and physical sector sizes, then GPT really doesn't matter.
It is pretty easy to partition a disk with GPT using a hybrid MBR so that the Stage1 and uBoot loaders can still find the boot and root partitions (as long as they're in the 1st 2TB of the disk).
Do you know if the stage1 loader and uBoot can handle the 512-byte-logical-sectors-in-4K-byte-physical-sectors that the new Advanced Format drives use?