To the card manufacturer of course. They did supplied flawed cards which are failing to comply with SDHC specifications, so it is their fault. According to specification, card must not become corrupted in such scenario when power dropped for some reason. At very most, some files can be damaged but card itself should become alive. I suspect you can encounter such corruption not just in Nokia n800 only. So, manufacturer MUST replace completely failed cards under warranty conditions.Solely their fault

Note: file system corruption file system corruption while card itself is alive is probably up to you.Card manufacturer is not responsible for the fact you or your device 've wrote data that are not looking like valid file system.Try to recover MBR and partition table with according software.If this fails and card seems to be totally dead, you have to request card replace\repair under warranty since you did nothing wrong against SDHC spec's.

Let's admit that it looks like there is card vendors who does not suffers from this bug and obey SDHC specs better.At least I was not able to corrupt my Kingston SDHC 8Gb card while doing everything described in this bug.Yes, I did downloaded huge 700 Mb file over wi-fi to SDHC card and device entered sleep mode and was awakened by me several times, etc.Yes, I did performed massive file transfers. Card is still alive.

P.S. and damn, do not tell about internal and external slot differences.That's annoying and lame.There is n800 scheme floating around in the web and you can see, both slots are attached to "Menelaus" chip.They should be electriacally identical.