I have doubts the n900 usb is very usable as host. Presumably for their production kernel nokia fixed almost all problems they could find related to peripheral but did not prioritize host. I don't know how many changes there were between 2.6.28 and 2.6.29 for usb, but there are 30 patches for usb against linux-omap-2.6.29 in the openembedded kernel.