For some reason or the other, my USB Mass Storage Device (ie. USB Stick) is greyed out in VirtualBox 3.1.2 on a OS X 10.6.2 host.
According to “USB Devices unavailable/grayed-out due to permission problem” on the VirtualBox Forums, this seems to be a known defect.
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Update:
It turns out, that it’s possible to access the USB Mass Storage Device after unmounting it in the OS X host. Kinda logical, if you think about it

