Good news is the Cardbus slots do work with Linux (tested with a USB 2.0 card)
Bad news is it screws up audio - and trying something with audio seems to have caused a kernel panic. Unfortunately my kernel tainting atheros wifi card was in the thinkpad at the time, so I'll have to repeat it without the wifi card to send off a bug report.
I may just disable the sound driver all together if it is an issue - I don't need audio.
I haven't tried the UltraBay yet - the dock came with a floppy drive in it (so now I have two - and I never used the one ...) or the PCI slot but both are at least reported to work in Linux by others (with some restrictions, such as no hot swapping)
But the CardBus slot does in fact work. So I'm happy
Now I'm off to see if I can repeat the audio related panic sans tainting madwifi module so I can bother the Fedora kernel maintainer



