Aaron... Many framebuilders make custom threadless stems.

Eric Estlund @ Winter Bikes comes to mind first, Dimitri @ Meech has made some as well.

The VO threadless stems are being phased out, I think, they said there wouldn't be any new orders last time I asked about a size being restocked. Having said that, they are just logo'd Taiwanese pieces (like all their stuff) and can be had from any QBP dealer as 'Dimension' or 'Civia' stems, and the Tall Stack is sold by other "brands" as well.