in that case the debugging will be a little harder, I guess... wish I had some more knowledge about electric circuits... cb22, if you have some time left, you could also try some combinations of

echo host > /sys/devices/platform/musb_hdrc/mode
echo H > /proc/driver/musb_hdrc
echo M > /proc/driver/musb_hdrc

... or also adding the FORCE_FS/FORCE_HS options to the switch (and testing that)...

did you try this with powered hub? it's possible, that we won't get any power from n900 itself...

maybe the echo M > ... isn't enough - the controller may be switched to host mode, but for some reason, the host mode information isn't propagated back to the musb_hdrc driver (does it show "host" somewhere in the sys files?)..