There's a guy selling a kit for the N810 that lets you use full-size SD cards. Currently, it only works with the Mugen extended battery kit, because he's having problems getting a good, solid custom cover made. EDIT: There's another problem; the Mugen battery kits seem to be "out of stock", even at the supplier's website.

All that having been said, I'm sticking with my N800 until I see what the new year brings in terms of new Maemo devices. I can wait another 6 months for the news...