It's a proprietary Dell connection. They've done this for years with a number of their video cards. You'll need a (you got it - proprietary) splitter that will likely give you two VGA outs or a DVI+VGA.
Yeah, it's a splitter connection that Dell uses mostly with their Precision desktops. I see it around the office all the time; they either split into 2 x DVI, 2 x VGA or 1 x DVI and 1 x VGA.
Was going to say the same thing, it's not a Dell Proprietary connection... it just combines 2 DVI/VGA outputs into 1 port. which is great for single-slot quad-DVI cards or low-profile dual DVI cards.
This is not proprietary. This is not Dell specific. This is not low profile card specific.
It is used for multiple monitors. Many Quadro and Matrox cards have it for multiple monitor support. I even have an ATI X2400 at my desk that has this connector.
We use these cards for our 12 headed (and 10 headed) beasts that we drive at work. Our help desk wall is composed of 2 PCs running 3 video cards each (22 monitors total). Each video card h(in my sistuation) has this connector because it can drive 4 monitors.