I'm running Linux Mint 12 x64 and can't get the latest virtualbox-4.1 update through apt.
I have the following line in my /etc/apt/sources.list:
deb http://download.virtualbox.org/virtualbox/debian oneiric contrib
Launching VirtualBox (currently at v4.1.6) shows an alert that a new version (v4.1.20) is available. Visiting the Packages file on the repo page shows v4.1.20 as the currently available version.
I can only assume a conflict or missing dependency exists somewhere, but I've no idea where to start looking for it.
Apt doesn't report any failures on the repos, or that virtualbox is being held back.