I've been working on an embedded linux appliance (actually, a continuation of my senior project), which uses initramfs root filesystem all rolled up with the kernel image, which is nice because then you only have one file to transfer around for upgrades and stuff. My latest kernel compile produced and "Invalid kernel module format" error every time I tried to load a module. Bad news, since my SATA and network drivers are compiled as modules.
I found help at these 2 sites, and between the 2 I'm sure I'll have the ammo I need to fix it up. If not, I'll be making another post shortly...