I've had cards that refuse to mount in the N800, the info bubble says "card is corrupt" but when I pop the card into a Windows XP card reader XP mounts it just fine with no hint of corruption. Interestingly, if I then insert the card back into the N800 the card is mounted without a problem.

It's as if something is being "corrupted" in the vfat filesystem which trips up the N800, and Windows will reset the "corruption" without a murmur. This suggests the N800/Linux vfat implementation is perhaps incomplete or over sensitive to some benign feature in the filesystem.