tl;dr

I have rebased my n900-v2011.06 branch on to v2011.12 which uses the omap_hsmmc driver instead of the omap3_mmc legacy driver. You can find this in the branch n900-v2011.12 in my github repo. It boots the nemo kernel correctly.

I also tested the u-boot binary in the first post of this thread, and it gives the -110 timeout errors as reported.