A caveat to those using the SpeedMod kernel: in its clockworkmod recovery, internal and.external flash memory mount points are exchanged. And this is very dangerous.
Yesterday, after editing my datafs and ums partitions to give more space to apps (4GB instead than 2) I tried to format my internal flash in recovery, silly me.
And I gave the command "format /emmc" in recovery. One second after, I reminded that those mount points are inverted....
But my external sdcard was already blank formatted. Everything was kaputt, including my latest nandroid backup (did I say I hadn't restored./data that far?), photos, videos, documents, firmwares...
Luckily I had a nandroid from last month, with docs backup, and part of my recent files could be found and restored with testdisk.
But it took me several hours to put it back almost as before my silly command.

So, the point of this story is: beware SpeedMod recovery and its borked mountpoints!