@Pali - confirmed, both Maemo and Ubuntu throw -110 errors for mmcblk1 (eMMC), when started with run sdboot. SD card is rock stable with modified kernel (2.6.37) I am using.

Would you give me a hint where u-boot enables eMMC? I will disable code which enables and will check how is the siuation.

Having in mind that one of the major differences between your and stskeeps' u-boot is internal memory being enabled by yours, I am almost sure your u-boot leaves eMMC in a state from which kernels cannot recover. And while it is definitely a bug in the kernel, I think we should do our best to workaround it in u-boot.