I applied the linux SDHC patch by Philip Langdale and recompiled the kernel. I can now see both my 4GB SDHC cards. I can write and read too. However, I just tried creating a 1.8Gb file using dd and after a short time I got a reboot. Only seems to have written 60Mb of it. Still, I doubt it'll be long before we've got SDHC support