The USB code in VirtualBox is not open-source.The ubuntu repository is the open version,so the open source edition of VirtualBox doesn't have USB function.It's easy enough to install the full one from virtualbox's website.
As an update: since version 4, they re-architected VirtualBox so that the standard distribution is fully open-source, and the proprietary features have been moved off into an extension pack. So you can install the Ubuntu package, and download the extension pack from Oracle.
The USB code in VirtualBox is not open-source.The ubuntu repository is the open version,so the open source edition of VirtualBox doesn't have USB function.It's easy enough to install the full one from virtualbox's website.
As an update: since version 4, they re-architected VirtualBox so that the standard distribution is fully open-source, and the proprietary features have been moved off into an extension pack. So you can install the Ubuntu package, and download the extension pack from Oracle.