32GB SDHC cards should work in the N800 using the SDHC kernel, however I've never yet seen even a 16GB SDHC card available for retail (though they have been announced for release later this year) - I doubt we'll see 32GB SDHC cards until well into 2008.

8GB SDHC cards are plentiful, work perfectly with the N800 SDHC kernel and are quite reasonably priced.

SDHC Kernel if you need it - install with the Linux flasher, doesn't remove installed applications etc. (which is a good thing).