This has been talked about with much confusion, but Koen pointed out that SDHC cards DO work in one of the OZ (or maybe it's Angstrom?) releases. It has been debated that SDHC cards require different hardware as well as software, but this has been shown not to be the case. So apparently the linux-rp 2.6.20 kernels will work with SDHC cards.
As for out-of-the-box Zaurii, an SDHC card will most definitely not work.