There are definitely issues related to SDHC support. Crediar added this support and I have barely had a chance to look into this in great detail, but there are definitely issues. Some are related to preloader and some are not.
I have 6 x wii consoles on hand to test with and 3 SDHC cards and one micro SDHC with adapter. I have had mixed results across various different firmwares, which make no logical sense at all. Some work some of the time, some work all of the time and some don't work at all. To the poster who said JODI 0.29 broke SDHC on his wii. That's a technical impossibility. The source for 0.29 was never released and a simple hex hack to change HAXX to JODI would not have inflicted on SD loading. There has to be another factor in his case, which may or may not be related to issues with preloader.
I'm currently working on the following (in order of priority):[*]More stability on auto booting dol files[*]Better compatability for SD/SDHC cards[*]USB support[*]WAD Installer / Uninstaller (no ability to remove sm/ios)[*]Possibility of installing and playing chip tunes (aka: keygen music)[*]Power down and reset from within preloader/phpgeek