Over the weekend Stephen Moeller contributed a bunch of patches to the Vmbuilder repository for Virtualbox support as well as fixing up the Debian packaging. You can examine them at the usual place(1), but be forewarned that I haven't tested them just yet. I'll get these off to Bzed tomorrow once I can be bothered to go downstairs and hook up an ethernet cable for Debian. And, of course, the usual machinations of pulling in changes from the vmbuilder trunk and bzed debian branch.
P.S. A little background - my Dell Studio 1535, while otherwise being a good machine, is cursed with a Broadcom Wifi card. I would rather not install non-free drivers on my Debian install after having a few bad experiences using the NVIDIA drivers on Debian on an older machine. So instead I go downstairs and physically connect the Lappy-486 to the home network.