[johannes1234321]

VirtualBox itself is GPL3 licensed. However the Addon for fast USB etc. which is an extra download is proprietary. To my understanding Sun tried to open source that as well, but it contained third party code they couldn't open up.

[tssva]

As of this release the USB stuff is now included in the opensource base.

[johannes1234321]

Oh nice, then I don't need that extension anymore. (RDP, disk encryption, netboot seem to be proprietary only, which aren't things I use on that layer in the stack)