Originally Posted by Orochi
Funny - I'm using a 4gb SDHC card with no problems, other than it seems to suck up power a little when accessing the card.
You'll probably find that the device will not recognize more than 2GB on the card, though, if there's no firmware support for SDHC.
SDHC support should be a firmware issue, not a hardware one. Given that the Kobo is based on the Netronix EB600, the card controller almost certainly supports SDHC.