After upgrading to new Mac OS Lion, my MacFuse ceased to work and I could not mount any USB drive I have. Uninstalling MacFuse is not an option. It seems the upgrade broke something there. I found a way to actually uninstall it and make mounting works again. OSXFUSE is the word. Download and install it. Remember to click the option to provide MacFuse layer, which would help us to uninstall MacFuse properly.