I've started working on a driver for the Secure Digital Host Controller
specification. This seems to be used by the majority of the controllers
found in todays PCs, so this driver would add support for a lot of
chips. Information is scarce so I do not know if this driver will get
production ready, but for those of you willing to live dangerously:
http://mmc.drzeus.cx/wiki/Linux/Drivers/sdhci
Rgds
Pierre