If you look through the HCL you’ll see we list the K1 and K2 cards from nVidia. These are not the only cards supported (as of View 5.3/vSphere 5.5 at the time of writing). Check out KB2058778.
One of the newer features from vSphere 5.5 is the ability to vMotion (and following to that, DRS load-balance) virtual machines that utilize these cards (provided the cards are on both sides). If the settings are set to automatic when vMotion is done and the card does not exist on the destination, then the soft vDGA 3-D will be used. If the setting is set explicitly to hardware video card, then no vMotion can occur if the destination does not have a matching card.