I just booted nevada b20 on my IBM t43p with a Sandisk 512 MB CF card in a Hagiwara sys-com HAD-EX5CF01 Compact Flash/Microdrive Adapter. The adapter goes into the Express Card slot (above the one Cardbus slot).
It appears to work fine - volume management opens a file manager window and the files/directories appear. I don't know if any other Express Card adapters will work with Solaris Express. Stuart This message posted from opensolaris.org