Sounds to me like a mismatch between the kernel and the module. I couldn't find any kernel modules within the cpio archive or ubifs so my guess is that these are coming from the rootfs of Harmattan (is that right juiceme?). If this is the case, the new kernel probably differs sufficiently that it would cause the problem. One possible solution could be to bundle the newly built modules with ubiboot and mount them over the top the rootfs.
juiceme, what's the reason for the new ubiboot kernel? Has anything changed there? I never bothered to flash the new ubiboot kernel as the changes I submitted didn't require them so I'm still on the previous kernel (0.3.6 tiny) and have no problems with loading g_multi.