I'm curious as to why you're using a bleeding edge kernel. What version do already-working Android phones use? It seems that an added variable is unnecessarily being introduced. Or am I missing something? Also, maybe the 2.6.27 Fremantle patches are compatible with Diablo. Do you see where I'm going? My opinion is that you should create a hybrid kernel based on already-running devices.

Does Android use an initfs? If not, maybe it should if it's going to run on Nokia tablets with 2 SDHC slots. Maybe you could more easily capture boot information. You should be able to create a hybrid initfs and bootmenu from the Diablo base. And although we want to be less embedded in the long run, I think talk about a grub-like boot partition is just another vaporware barrier to early usability. Sorry if I'm less informed than I should be; I'm just a proponent of walking before running.