Hi,
As it's been recently found out (thanks to Ward for spotting this), there was a problem in the Linux loader of GRUB that is used on coreboot, that prevented Linux from finding its Initrd images under certain setups (when both Initrd and amount of RAM surpassed a certain limit). It seems that Linux has certain requirements on Initrd location which our new loader didn't know about.
This problem has just been fixed in latest SVN. I've tested with a few different images (including those from Debian and Ubuntu), and everything seems to be fine now.
I'd like to encourage you folks to try the latest revision. If coreboot specific problems are found, feel free to let grub-devel@gnu.org know (or mail me directly if you like).