The latests/greatest/fastest kernel for the N800 as of this date is the kernel referenced in the first post of this thread... the patch author chose to name the new kernel mmc-* whereas before he used the sdhc-* prefix... no big deal, as this patch fixes up both SD and MMC support.

Follow the wiki instructions but use the new filename (mmc-kernel-4.2007.26.bin) wherever it mentions the old filename (sdhc-kernel-3.2007.10.bin).

What's the difference? mmc-kernel-4.2007.26.bin supports the latest Nokia kernel, while sdhc-kernel-3.2007.10.bin supports the kernel from the previous Nokia 3.2007 firmware release - the SD/MMC support is the same in both files, but if you installed sdhc-kernel-3.2007.10.bin you will be missing all the recent kernel bug fixes and improvements introduced with the 4.2007.26-8 Nokia firmware release.